<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:2bdb094c-ae09-4ea3-a966-8508ad4646a0,g:ff4b8065-d4db-4713-b18b-19434889a152-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/CoverPage" xlink:type="simple" xlink:href="sui-20210331.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/CoverPage" xlink:type="extended" id="if8042256440b45d79f1b77552c770af0_CoverPage"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedBalanceSheets" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedBalanceSheets"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedBalanceSheets" xlink:type="extended" id="if1602226390e452485968dd087f4953b_ConsolidatedBalanceSheets">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Land_d6771835-8af5-4868-93a9-598b61954d79" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Land"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_Land_d6771835-8af5-4868-93a9-598b61954d79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RealEstateInvestmentPropertyLandImprovementsAndBuildings_4cafe548-4f89-47fa-8446-40657e55eafa" xlink:href="sui-20210331.xsd#sui_RealEstateInvestmentPropertyLandImprovementsAndBuildings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_sui_RealEstateInvestmentPropertyLandImprovementsAndBuildings_4cafe548-4f89-47fa-8446-40657e55eafa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RentalProperties_a328c681-8994-483c-80c2-0e232aa37466" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RentalProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_RentalProperties_a328c681-8994-483c-80c2-0e232aa37466" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesGross_16cb146a-1010-4072-b73f-02e60d8318cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_FurnitureAndFixturesGross_16cb146a-1010-4072-b73f-02e60d8318cd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyAtCost_eb3ec8e9-4e8d-453a-a1f1-6d2b4179d423" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyAtCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyAtCost_eb3ec8e9-4e8d-453a-a1f1-6d2b4179d423" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation_6128d216-60bc-459a-91ce-b721432b4db7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation_6128d216-60bc-459a-91ce-b721432b4db7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyNet_b6f95df8-7295-4d18-abeb-5c2e16da6e0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyNet_b6f95df8-7295-4d18-abeb-5c2e16da6e0d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_75e6528c-c0ab-4415-b398-4ad40d05ee26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_75e6528c-c0ab-4415-b398-4ad40d05ee26" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bfa1b26a-0b62-47c4-a91f-f1a0e49b07b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bfa1b26a-0b62-47c4-a91f-f1a0e49b07b1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecurities_9594070d-e178-4b2a-86db-ef3f6a71d404" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_MarketableSecurities_9594070d-e178-4b2a-86db-ef3f6a71d404" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedHomes_0f03e495-1578-4f03-a26a-97ffd5dffbc5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryFinishedHomes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_InventoryFinishedHomes_0f03e495-1578-4f03-a26a-97ffd5dffbc5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsAndNotesReceivableNet_72739495-ff3b-46d6-b6d7-b94c350b04c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsAndNotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_AccountsAndNotesReceivableNet_72739495-ff3b-46d6-b6d7-b94c350b04c5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_10a54023-6a28-4d31-a1b7-186d25ce41ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_10a54023-6a28-4d31-a1b7-186d25ce41ab" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_e9acea46-2f60-45d7-947b-efcde77ef251" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_OtherAssets_e9acea46-2f60-45d7-947b-efcde77ef251" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_4098e481-32ed-4075-8a80-c27ee62149e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_311cfcde-e0a5-4880-ba89-f3e94422ce0f" xlink:to="loc_us-gaap_Assets_4098e481-32ed-4075-8a80-c27ee62149e2" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_ff171922-79e5-46fb-95e5-ff9d44e66081" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_SecuredDebt_ff171922-79e5-46fb-95e5-ff9d44e66081" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherBorrowings_bd366df2-83c7-423c-92be-b5bbc920edeb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_OtherBorrowings_bd366df2-83c7-423c-92be-b5bbc920edeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_c04e5187-c6cb-45ac-ae03-97c2140d5e3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_c04e5187-c6cb-45ac-ae03-97c2140d5e3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_2cb73af5-491b-4e6b-b0c8-8181e61c8044" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_LineOfCredit_2cb73af5-491b-4e6b-b0c8-8181e61c8044" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_fd97a8b5-9da5-4745-969a-9bc98105459d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_fd97a8b5-9da5-4745-969a-9bc98105459d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_818b1a5e-22d0-442a-bb8b-556f501909e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_ContractWithCustomerLiability_818b1a5e-22d0-442a-bb8b-556f501909e0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrentAndNoncurrent_08edb374-9859-4d03-9b5f-6ab11e6887ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_AccountsPayableCurrentAndNoncurrent_08edb374-9859-4d03-9b5f-6ab11e6887ef" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_b0b054bb-6986-4246-aeb1-fe1b32178f57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_OtherLiabilities_b0b054bb-6986-4246-aeb1-fe1b32178f57" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_cfe466bb-178c-4c57-b506-2d41032259ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_us-gaap_Liabilities_cfe466bb-178c-4c57-b506-2d41032259ae" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquity_2fa48ba1-e93e-4206-9a62-2583fe287e23" xlink:href="sui-20210331.xsd#sui_TemporaryEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_7c60bded-4f10-4035-b93e-28403fd27d26" xlink:to="loc_sui_TemporaryEquity_2fa48ba1-e93e-4206-9a62-2583fe287e23" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_22ef74b2-7736-4039-a871-c0669bc04cc2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_CommitmentsAndContingencies_22ef74b2-7736-4039-a871-c0669bc04cc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredCarryingAmount_de774666-7a57-4ff7-b8ea-cefa0e778436" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityPreferredCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityPreferredCarryingAmount_de774666-7a57-4ff7-b8ea-cefa0e778436" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount_5766f9fe-bb08-46db-993d-0344f876429e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_RedeemableNoncontrollingInterestEquityCommonCarryingAmount_5766f9fe-bb08-46db-993d-0344f876429e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_48cb2c6c-f67c-47c2-a018-b693710d2a15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_CommonStockValue_48cb2c6c-f67c-47c2-a018-b693710d2a15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_4a05e6c8-0cad-4a72-8a19-7eecd58041a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_AdditionalPaidInCapital_4a05e6c8-0cad-4a72-8a19-7eecd58041a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_3479f12b-6465-442a-92fb-c913273d93e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_3479f12b-6465-442a-92fb-c913273d93e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDistributionsInExcessOfNetIncome_122c25f8-96ce-47b2-8e74-ee0c5fd7d2e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDistributionsInExcessOfNetIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_AccumulatedDistributionsInExcessOfNetIncome_122c25f8-96ce-47b2-8e74-ee0c5fd7d2e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_94c96ce8-b4c1-401f-a268-08baad65d858" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_StockholdersEquity_94c96ce8-b4c1-401f-a268-08baad65d858" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestAbstract_b3093116-721b-4233-ae1e-6b9e0742eaeb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_NoncontrollingInterestAbstract_b3093116-721b-4233-ae1e-6b9e0742eaeb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestInOperatingPartnerships_0a596c99-c9ae-42c8-933b-1435c85c0a23" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestInOperatingPartnerships"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncontrollingInterestAbstract_b3093116-721b-4233-ae1e-6b9e0742eaeb" xlink:to="loc_us-gaap_MinorityInterestInOperatingPartnerships_0a596c99-c9ae-42c8-933b-1435c85c0a23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestInVariableInterestEntity_ce8cb88b-28ab-447f-bbec-696fe13150b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestInVariableInterestEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncontrollingInterestAbstract_b3093116-721b-4233-ae1e-6b9e0742eaeb" xlink:to="loc_us-gaap_NoncontrollingInterestInVariableInterestEntity_ce8cb88b-28ab-447f-bbec-696fe13150b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_b2771996-51cd-44ea-87aa-c5a0bb10e2c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncontrollingInterestAbstract_b3093116-721b-4233-ae1e-6b9e0742eaeb" xlink:to="loc_us-gaap_MinorityInterest_b2771996-51cd-44ea-87aa-c5a0bb10e2c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b2b17526-c9ce-439e-8355-77acd065cd1b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_033bb65e-b525-4f4d-9e37-60109d13e262" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b2b17526-c9ce-439e-8355-77acd065cd1b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_08d51843-549f-4df6-8008-306a1b50d254" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_08d51843-549f-4df6-8008-306a1b50d254" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_e8c057f1-7c30-408d-9816-21cb2f7fd312" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_Goodwill_e8c057f1-7c30-408d-9816-21cb2f7fd312" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_0cb40d07-2dde-444a-8318-7298b33a6e57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_0cb40d07-2dde-444a-8318-7298b33a6e57" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_085c4089-e940-46d9-8f5b-a18947ed0129" xlink:to="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_65dc1db7-89c1-406f-8dd2-9f3a1fa50007" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_65dc1db7-89c1-406f-8dd2-9f3a1fa50007" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_65dc1db7-89c1-406f-8dd2-9f3a1fa50007_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_65dc1db7-89c1-406f-8dd2-9f3a1fa50007" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_65dc1db7-89c1-406f-8dd2-9f3a1fa50007_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ef17aa77-4721-487e-a85b-f2b555e198a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_65dc1db7-89c1-406f-8dd2-9f3a1fa50007" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ef17aa77-4721-487e-a85b-f2b555e198a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9406846f-fb92-46c9-953a-ba9889d71277" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ef17aa77-4721-487e-a85b-f2b555e198a0" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9406846f-fb92-46c9-953a-ba9889d71277" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_854256fa-907e-4ebb-9bb6-630e95458a3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9406846f-fb92-46c9-953a-ba9889d71277" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_854256fa-907e-4ebb-9bb6-630e95458a3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_3617663a-86ac-4c0a-ad80-adab6e420aed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_3617663a-86ac-4c0a-ad80-adab6e420aed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3617663a-86ac-4c0a-ad80-adab6e420aed_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3617663a-86ac-4c0a-ad80-adab6e420aed" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3617663a-86ac-4c0a-ad80-adab6e420aed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_410a154d-d669-4f2a-aace-57771bf8f36e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3617663a-86ac-4c0a-ad80-adab6e420aed" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_410a154d-d669-4f2a-aace-57771bf8f36e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PreferredEquityMandatorilyRedeemableMember_2c0af799-f5fc-4841-b898-8d88b750bf20" xlink:href="sui-20210331.xsd#sui_PreferredEquityMandatorilyRedeemableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_410a154d-d669-4f2a-aace-57771bf8f36e" xlink:to="loc_sui_PreferredEquityMandatorilyRedeemableMember_2c0af799-f5fc-4841-b898-8d88b750bf20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_076f146d-7c07-4185-b07c-e2a0f34ee5e7" xlink:href="sui-20210331.xsd#sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_410a154d-d669-4f2a-aace-57771bf8f36e" xlink:to="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_076f146d-7c07-4185-b07c-e2a0f34ee5e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1a019013-eb3c-4899-bc45-93766b701611" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1a019013-eb3c-4899-bc45-93766b701611" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1a019013-eb3c-4899-bc45-93766b701611_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1a019013-eb3c-4899-bc45-93766b701611" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1a019013-eb3c-4899-bc45-93766b701611_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9b97d817-c329-403a-8554-e9be0030ec1f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1a019013-eb3c-4899-bc45-93766b701611" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9b97d817-c329-403a-8554-e9be0030ec1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_81fb6db0-b153-43d7-9bdf-fa53b2feef99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_9b97d817-c329-403a-8554-e9be0030ec1f" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_81fb6db0-b153-43d7-9bdf-fa53b2feef99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:to="loc_us-gaap_StatementClassOfStockAxis_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf" xlink:to="loc_us-gaap_ClassOfStockDomain_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5ae7fedc-f512-4731-ba88-3a6d8c35b2bf" xlink:to="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_d9a344bf-aadd-45a2-84a0-1ae6a24053ed" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:to="loc_sui_SeriesA4PreferredStockMember_d9a344bf-aadd-45a2-84a0-1ae6a24053ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredOpUnitsMember_6e908657-4f63-4e7d-8ff4-0974a836b299" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:to="loc_sui_SeriesA4PreferredOpUnitsMember_6e908657-4f63-4e7d-8ff4-0974a836b299" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesDPreferredOPUnitsMember_9abb8882-2031-40f9-8b0e-a4d8e322580f" xlink:href="sui-20210331.xsd#sui_SeriesDPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:to="loc_sui_SeriesDPreferredOPUnitsMember_9abb8882-2031-40f9-8b0e-a4d8e322580f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_5e39ff03-ea1f-4889-b465-1a962c07191b" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_5e39ff03-ea1f-4889-b465-1a962c07191b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesGPreferredOPUnitsMember_38f5022a-1944-4e6e-afad-1603716bc6f2" xlink:href="sui-20210331.xsd#sui_SeriesGPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b4556965-da4c-4a4b-9e4f-6de46ec94780" xlink:to="loc_sui_SeriesGPreferredOPUnitsMember_38f5022a-1944-4e6e-afad-1603716bc6f2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_57b809e1-09a9-4f2e-a2be-e2080f5f433a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_aff0063f-ab0f-4b3c-98ce-7dcc49bd3942" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_57b809e1-09a9-4f2e-a2be-e2080f5f433a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_57b809e1-09a9-4f2e-a2be-e2080f5f433a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_57b809e1-09a9-4f2e-a2be-e2080f5f433a" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_57b809e1-09a9-4f2e-a2be-e2080f5f433a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_5f85ca6b-a834-49c4-b710-6e72eb0b749e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_57b809e1-09a9-4f2e-a2be-e2080f5f433a" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_5f85ca6b-a834-49c4-b710-6e72eb0b749e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_7bb8fc13-8ed1-4868-9ff5-0efc5004126d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_5f85ca6b-a834-49c4-b710-6e72eb0b749e" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_7bb8fc13-8ed1-4868-9ff5-0efc5004126d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedBalanceSheetsParenthetical"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" id="i225d5db21fd345cea17cb8eb2a7ed6ec_ConsolidatedBalanceSheetsParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyNet_07bd62d1-26b4-4d69-8b11-69b55be02834" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyNet_07bd62d1-26b4-4d69-8b11-69b55be02834" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_c8d94068-3108-4deb-bad1-f33b96b0a495" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_OtherAssets_c8d94068-3108-4deb-bad1-f33b96b0a495" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_dae3703c-844b-4090-bfd7-cc57ff26cacf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_SecuredDebt_dae3703c-844b-4090-bfd7-cc57ff26cacf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityConsolidatedVIE_6cd43d17-b24b-479b-98db-b457834fa88f" xlink:href="sui-20210331.xsd#sui_TemporaryEquityConsolidatedVIE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_sui_TemporaryEquityConsolidatedVIE_6cd43d17-b24b-479b-98db-b457834fa88f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_0056bd5a-7eac-4710-b104-6f25b354a07a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_0056bd5a-7eac-4710-b104-6f25b354a07a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_f60ec4db-9e80-4cf8-a9d3-2fe6840f48cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_OtherLiabilities_f60ec4db-9e80-4cf8-a9d3-2fe6840f48cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_04469802-760c-452f-9fc6-efb6af2c1e5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_04469802-760c-452f-9fc6-efb6af2c1e5a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_3054744f-9807-4773-8604-5ae59aa4d51e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_3054744f-9807-4773-8604-5ae59aa4d51e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_a546bafc-7a6d-4cbb-b008-800a6cf6721e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_a546bafc-7a6d-4cbb-b008-800a6cf6721e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_cbccbe7b-5917-49e3-8a95-6806f02aa156" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_cbccbe7b-5917-49e3-8a95-6806f02aa156" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_48bb541f-37e6-42c6-9ab4-0aed985990a8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_CommonStockSharesIssued_48bb541f-37e6-42c6-9ab4-0aed985990a8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_afeee6d5-c8fe-4810-8761-63d1b10bce51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_afeee6d5-c8fe-4810-8761-63d1b10bce51" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_06488db1-7332-475d-b3d4-2bcf9f662867" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_d9f6bfcb-e927-4c93-839d-4e8b1d3f1823" xlink:to="loc_us-gaap_StatementTable_06488db1-7332-475d-b3d4-2bcf9f662867" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_4c8add68-d0ed-4866-a52d-b3f41623832f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_06488db1-7332-475d-b3d4-2bcf9f662867" xlink:to="loc_us-gaap_StatementClassOfStockAxis_4c8add68-d0ed-4866-a52d-b3f41623832f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4c8add68-d0ed-4866-a52d-b3f41623832f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4c8add68-d0ed-4866-a52d-b3f41623832f" xlink:to="loc_us-gaap_ClassOfStockDomain_4c8add68-d0ed-4866-a52d-b3f41623832f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_836ff93b-85b1-432a-a0d3-5dd8d8540717" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4c8add68-d0ed-4866-a52d-b3f41623832f" xlink:to="loc_us-gaap_ClassOfStockDomain_836ff93b-85b1-432a-a0d3-5dd8d8540717" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_ad2752ea-9c3d-44bc-8ab9-894d36e667fc" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_836ff93b-85b1-432a-a0d3-5dd8d8540717" xlink:to="loc_sui_SeriesA4PreferredStockMember_ad2752ea-9c3d-44bc-8ab9-894d36e667fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_06488db1-7332-475d-b3d4-2bcf9f662867" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_5fe4aa88-5ec5-4496-9073-5de88610185e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_9ba4af3b-0cdb-4b5d-9760-509b5edd8f3b" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_5fe4aa88-5ec5-4496-9073-5de88610185e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedStatementsOfOperations" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedStatementsOfOperations"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedStatementsOfOperations" xlink:type="extended" id="i2e592aece022443bbb83426ab4754dc7_ConsolidatedStatementsOfOperations"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedStatementsOfComprehensiveIncome"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" id="i840e748304d54f988afc4d34415aa7f6_ConsolidatedStatementsOfComprehensiveIncome"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedStatementsOfCashFlows"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" id="i6c9a645e2b05435098d24d821e5d5050_ConsolidatedStatementsOfCashFlows">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_bd46476c-e3ca-499b-b57f-f08d12019fab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_bd46476c-e3ca-499b-b57f-f08d12019fab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_ffbb1d0a-e7ba-48cd-881c-bb50aea6a403" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_bd46476c-e3ca-499b-b57f-f08d12019fab" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_ffbb1d0a-e7ba-48cd-881c-bb50aea6a403" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireAndDevelopRealEstate_95027edf-7b17-4899-ae0d-52c301480f07" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireAndDevelopRealEstate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_PaymentsToAcquireAndDevelopRealEstate_95027edf-7b17-4899-ae0d-52c301480f07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_fcb2c66f-18f6-448e-8ef5-d80284a6d557" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_fcb2c66f-18f6-448e-8ef5-d80284a6d557" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_f5ff4d6b-d9c1-4d58-86a2-676131b9a455" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_f5ff4d6b-d9c1-4d58-86a2-676131b9a455" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfOtherProductiveAssets_8ba8814f-77ba-4a0a-bb7f-fc49a9c1fd2c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromSaleOfOtherProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_ProceedsFromSaleOfOtherProductiveAssets_8ba8814f-77ba-4a0a-bb7f-fc49a9c1fd2c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Issuanceofnotesandotherreceivables_169c55fc-2438-4194-b45b-84486a3bf01d" xlink:href="sui-20210331.xsd#sui_Issuanceofnotesandotherreceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_sui_Issuanceofnotesandotherreceivables_169c55fc-2438-4194-b45b-84486a3bf01d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RepaymentofNotesandOtherReceivables_c7d7d18b-baad-4fc8-b95e-e8bd75a027d9" xlink:href="sui-20210331.xsd#sui_RepaymentofNotesandOtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_sui_RepaymentofNotesandOtherReceivables_c7d7d18b-baad-4fc8-b95e-e8bd75a027d9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates_a5c107aa-80d8-435a-b9f0-c115ee212204" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates_a5c107aa-80d8-435a-b9f0-c115ee212204" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates_2b8b67ff-36a4-4a7d-b8d4-53c7094197be" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates_2b8b67ff-36a4-4a7d-b8d4-53c7094197be" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_fc9e251b-acda-47ca-8e57-99705d99a689" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_756d45a6-2ada-40e0-88c6-14cfe0def9d8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_fc9e251b-acda-47ca-8e57-99705d99a689" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_ed9fa454-1f33-4789-8485-bba9f7e9b9db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_ed9fa454-1f33-4789-8485-bba9f7e9b9db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_244be4c5-a964-422b-9728-3b699f3d392e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_244be4c5-a964-422b-9728-3b699f3d392e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_53eff7ca-937d-4d45-9982-1abbbdf00b62" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_53eff7ca-937d-4d45-9982-1abbbdf00b62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_8cf4045f-2089-4f8b-9e2e-336ea8bf967a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_8cf4045f-2089-4f8b-9e2e-336ea8bf967a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_54d37b01-d736-400b-80c4-df2c70ce4651" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_54d37b01-d736-400b-80c4-df2c70ce4651" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrepaymentPenaltyDebt_72b00735-3050-40db-a369-77b09a4a2127" xlink:href="sui-20210331.xsd#sui_PrepaymentPenaltyDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_sui_PrepaymentPenaltyDebt_72b00735-3050-40db-a369-77b09a4a2127" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock_4aff4ef5-3031-473e-af50-14aab7b5c21e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock_4aff4ef5-3031-473e-af50-14aab7b5c21e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DistributionsToStockholdersOpUnitHoldersAndPreferredOpUnitHolders_d2b063af-91fc-4318-9463-de6cfb94cc66" xlink:href="sui-20210331.xsd#sui_DistributionsToStockholdersOpUnitHoldersAndPreferredOpUnitHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_sui_DistributionsToStockholdersOpUnitHoldersAndPreferredOpUnitHolders_d2b063af-91fc-4318-9463-de6cfb94cc66" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_9bc777eb-9a07-48b6-ac09-8fece6637e22" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_9bc777eb-9a07-48b6-ac09-8fece6637e22" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_f679b801-4e93-4915-8707-6c61366f349d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_f679b801-4e93-4915-8707-6c61366f349d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_ad2a1ccb-7ef9-432d-8ce6-e3fcef0edae8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_ad2a1ccb-7ef9-432d-8ce6-e3fcef0edae8" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_912f8933-3f66-475d-9e38-9ae4a4fcbcdf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_912f8933-3f66-475d-9e38-9ae4a4fcbcdf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_3109a6e4-e9f5-4c22-9de1-1363e59795ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_3109a6e4-e9f5-4c22-9de1-1363e59795ff" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_aab926d1-dc44-4c26-acea-bdb6a0e78752" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6bc1ba69-aed9-4433-b079-772d66f8ee83" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_aab926d1-dc44-4c26-acea-bdb6a0e78752" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_a7f2cb76-6c81-446f-9c34-03573395ca4b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_3ebcfbb7-5b06-456d-b6b8-a1f3b6a07e45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:to="loc_us-gaap_InterestPaidNet_3ebcfbb7-5b06-456d-b6b8-a1f3b6a07e45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsOnMandatorilyRedeemableSecurities_5e6ed862-71ef-4f73-a43c-3c4dc4b25456" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DistributionsOnMandatorilyRedeemableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:to="loc_us-gaap_DistributionsOnMandatorilyRedeemableSecurities_5e6ed862-71ef-4f73-a43c-3c4dc4b25456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_6a345cc6-d1e5-4db3-bee0-4e821ea4e81a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_6a345cc6-d1e5-4db3-bee0-4e821ea4e81a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_d40d7bee-67d4-46e8-80c5-9d42ec9d0055" xlink:to="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_40b5d471-044e-41d9-a24e-09edf142e855" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_40b5d471-044e-41d9-a24e-09edf142e855" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_f1621b74-39ce-48d6-a8cb-c9d90e730efd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_us-gaap_Dividends_f1621b74-39ce-48d6-a8cb-c9d90e730efd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockAmountConverted1_a32d8fbd-624e-425d-a8b3-371fb5ed892c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockAmountConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_us-gaap_ConversionOfStockAmountConverted1_a32d8fbd-624e-425d-a8b3-371fb5ed892c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConversionOfSeriesAFourPreferredStock_7ee1d2a2-4631-4438-9409-aa68ea2365a0" xlink:href="sui-20210331.xsd#sui_ConversionOfSeriesAFourPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_sui_ConversionOfSeriesAFourPreferredStock_7ee1d2a2-4631-4438-9409-aa68ea2365a0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAssetsHeldForSale_f4961ce1-90af-4afe-b020-33671e4aac4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAssetsHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_us-gaap_IncreaseDecreaseInAssetsHeldForSale_f4961ce1-90af-4afe-b020-33671e4aac4c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationValueOfSharesIssued_9386727a-2c72-4327-ab23-3785867caf34" xlink:href="sui-20210331.xsd#sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationValueOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationValueOfSharesIssued_9386727a-2c72-4327-ab23-3785867caf34" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_StockIssuedDuringPeriodValueNewIssuesPreferredOPUnits_38cb1d33-591c-49ab-8ea6-b4bb1d4bfc94" xlink:href="sui-20210331.xsd#sui_StockIssuedDuringPeriodValueNewIssuesPreferredOPUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_sui_StockIssuedDuringPeriodValueNewIssuesPreferredOPUnits_38cb1d33-591c-49ab-8ea6-b4bb1d4bfc94" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_StockIssuedDuringPeriodValueNewIssuesSeriesA3PreferredOPUnits_ae8cf89b-505c-4efb-8a1c-f29fee4bc12e" xlink:href="sui-20210331.xsd#sui_StockIssuedDuringPeriodValueNewIssuesSeriesA3PreferredOPUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_sui_StockIssuedDuringPeriodValueNewIssuesSeriesA3PreferredOPUnits_ae8cf89b-505c-4efb-8a1c-f29fee4bc12e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationEscrow_5032a372-dd33-4b0d-a17b-065ab3bb629f" xlink:href="sui-20210331.xsd#sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationEscrow"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_sui_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationEscrow_5032a372-dd33-4b0d-a17b-065ab3bb629f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeTaxExpense_8ef828ad-0b1a-4f89-8c14-370b08a9066a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncashIncomeTaxExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_d1fd8e54-b75e-4908-8ed5-059fd3e9f777" xlink:to="loc_us-gaap_OtherNoncashIncomeTaxExpense_8ef828ad-0b1a-4f89-8c14-370b08a9066a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_dceb10ef-d566-4e6b-9898-036dc02550c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_63ba5404-872d-4386-acb0-4e2763b41a94" xlink:to="loc_us-gaap_StatementTable_dceb10ef-d566-4e6b-9898-036dc02550c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_dceb10ef-d566-4e6b-9898-036dc02550c2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323" xlink:to="loc_us-gaap_ClassOfStockDomain_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9572610a-a0f0-45ff-a0c5-bfc8f8f2b323" xlink:to="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_c0604da4-0a19-4000-88f2-5af1fceed782" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_c0604da4-0a19-4000-88f2-5af1fceed782" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonStockAndOPUnitsMember_b9bc7696-f1e8-4aa8-b6eb-6d4bd7e12e69" xlink:href="sui-20210331.xsd#sui_CommonStockAndOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_CommonStockAndOPUnitsMember_b9bc7696-f1e8-4aa8-b6eb-6d4bd7e12e69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtMember_2b6808d6-3aa3-402b-9f1a-3c66f349107b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_us-gaap_DebtMember_2b6808d6-3aa3-402b-9f1a-3c66f349107b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesDPreferredStockMember_91eb3508-15f7-4108-ab11-3cf45d8c1316" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesDPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_us-gaap_SeriesDPreferredStockMember_91eb3508-15f7-4108-ab11-3cf45d8c1316" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_41c79c8e-70d2-404f-a615-86b0d0d0c1d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_41c79c8e-70d2-404f-a615-86b0d0d0c1d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesB3PreferredOPUnitsMember_66a88dcd-ec56-49f0-8d93-c648b64df421" xlink:href="sui-20210331.xsd#sui_SeriesB3PreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_SeriesB3PreferredOPUnitsMember_66a88dcd-ec56-49f0-8d93-c648b64df421" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesEPreferredOPUnitsDomain_1813b68c-7c8f-4253-8eda-634c3c338ae5" xlink:href="sui-20210331.xsd#sui_SeriesEPreferredOPUnitsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_SeriesEPreferredOPUnitsDomain_1813b68c-7c8f-4253-8eda-634c3c338ae5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_475422cb-db28-426c-8e15-c6fed547f2eb" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_475422cb-db28-426c-8e15-c6fed547f2eb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesGPreferredOPUnitsMember_9f5408f0-60f9-44ce-a0c1-9832f04ee256" xlink:href="sui-20210331.xsd#sui_SeriesGPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_SeriesGPreferredOPUnitsMember_9f5408f0-60f9-44ce-a0c1-9832f04ee256" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DeferredLiabilityMember_43ff0ecd-7349-47bf-8008-018e66b09c55" xlink:href="sui-20210331.xsd#sui_DeferredLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_DeferredLiabilityMember_43ff0ecd-7349-47bf-8008-018e66b09c55" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ContingentConsiderationLiabilityMember_a476940b-56c9-4742-af51-17cc654ed7f0" xlink:href="sui-20210331.xsd#sui_ContingentConsiderationLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c5497e99-4adc-4ee5-904e-88f2875dbd41" xlink:to="loc_sui_ContingentConsiderationLiabilityMember_a476940b-56c9-4742-af51-17cc654ed7f0" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedStatementsOfCashFlowsParenthetical" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedStatementsOfCashFlowsParenthetical"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedStatementsOfCashFlowsParenthetical" xlink:type="extended" id="ia71c61e5d0064af7b5b114372dc76cab_ConsolidatedStatementsOfCashFlowsParenthetical"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedStatementOfStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedStatementOfStockholdersEquity" xlink:type="extended" id="i47d2802003bf45b88db827c3eeaec412_ConsolidatedStatementOfStockholdersEquity">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_373f62d9-d659-4e08-8d6d-950e7f546004" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInTemporaryEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_373f62d9-d659-4e08-8d6d-950e7f546004" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_2c72a11f-034e-44b2-867d-963615c0ed95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_2c72a11f-034e-44b2-867d-963615c0ed95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_c3d2d0b7-f0f1-47c5-8a18-f8f682ef8b41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityAccretionToRedemptionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_us-gaap_TemporaryEquityAccretionToRedemptionValue_c3d2d0b7-f0f1-47c5-8a18-f8f682ef8b41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityIssuanceofEquityUnits_891b542c-1cf4-4f16-902f-2107ee57a430" xlink:href="sui-20210331.xsd#sui_TemporaryEquityIssuanceofEquityUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_sui_TemporaryEquityIssuanceofEquityUnits_891b542c-1cf4-4f16-902f-2107ee57a430" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_77dbb059-df7e-4c1e-8b87-206406fcf756" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_77dbb059-df7e-4c1e-8b87-206406fcf756" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_6f3a42c0-c8fc-4654-b8fc-cf944642c0d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationsOfTemporaryToPermanentEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_6f3a42c0-c8fc-4654-b8fc-cf944642c0d7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityNetIncome_c5edeb59-eafd-457e-b295-ff41f4e3b7c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityNetIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_us-gaap_TemporaryEquityNetIncome_c5edeb59-eafd-457e-b295-ff41f4e3b7c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividends_22d32e23-d10c-4e30-96fa-acf2f42aac16" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_9d59a28b-c5ea-4ead-ad8d-5bf2bf3dbbe0" xlink:to="loc_sui_TemporaryEquityDividends_22d32e23-d10c-4e30-96fa-acf2f42aac16" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_7decad53-aea4-44af-bbf2-1cc7699b198f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_373f62d9-d659-4e08-8d6d-950e7f546004" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_fcbfa6e3-5474-46e9-a1e5-01703046fa63" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_fcbfa6e3-5474-46e9-a1e5-01703046fa63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_e70f556c-061c-4c6f-919a-a995857ce64f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_e70f556c-061c-4c6f-919a-a995857ce64f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_203e189f-73c1-4bb5-a960-1569acffa438" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_203e189f-73c1-4bb5-a960-1569acffa438" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityEquityInterestsIssued_a28213bb-7155-479e-8af7-a0e816b19d0c" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityEquityInterestsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_sui_VariableInterestEntityEquityInterestsIssued_a28213bb-7155-479e-8af7-a0e816b19d0c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_a9e2fc56-db7f-427a-a3d9-cdcd1b0d4df0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestDecreaseFromRedemptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_a9e2fc56-db7f-427a-a3d9-cdcd1b0d4df0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_StockBasedCompensationAmortizationAndForfeitures_f48ab32c-b772-40ea-88b6-c892eac79276" xlink:href="sui-20210331.xsd#sui_StockBasedCompensationAmortizationAndForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_sui_StockBasedCompensationAmortizationAndForfeitures_f48ab32c-b772-40ea-88b6-c892eac79276" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_ff224ba5-e65e-47b2-8f13-457ffc9f9b87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_ff224ba5-e65e-47b2-8f13-457ffc9f9b87" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NetIncomeLossIncludingPortionAttributabletoNoncontrollingInterestandReturnsfromPreferredStock_57110cdc-e9b5-4e26-ad5e-984c83d892a6" xlink:href="sui-20210331.xsd#sui_NetIncomeLossIncludingPortionAttributabletoNoncontrollingInterestandReturnsfromPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_sui_NetIncomeLossIncludingPortionAttributabletoNoncontrollingInterestandReturnsfromPreferredStock_57110cdc-e9b5-4e26-ad5e-984c83d892a6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RemeasurementOfNotesReceivableAndEquityMethodInvestments_bd3e20fa-5b1e-4f1a-a7ea-4300ab711df1" xlink:href="sui-20210331.xsd#sui_RemeasurementOfNotesReceivableAndEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_sui_RemeasurementOfNotesReceivableAndEquityMethodInvestments_bd3e20fa-5b1e-4f1a-a7ea-4300ab711df1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RemeasurementofNotesReceivableEquityMethodInvestment_ca30d3a9-b7fb-4e63-8f1c-370e376bfc9f" xlink:href="sui-20210331.xsd#sui_RemeasurementofNotesReceivableEquityMethodInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_sui_RemeasurementofNotesReceivableEquityMethodInvestment_ca30d3a9-b7fb-4e63-8f1c-370e376bfc9f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAssetsHeldForSale_c99249bd-6783-4dda-b317-ea612bccb48a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAssetsHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_IncreaseDecreaseInAssetsHeldForSale_c99249bd-6783-4dda-b317-ea612bccb48a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_df936388-5fdc-4ba4-908c-34bd8a0c6e65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_NetIncomeLoss_df936388-5fdc-4ba4-908c-34bd8a0c6e65" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCash_04139d81-3619-43e0-8619-319cc001f404" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_227ea4cb-6e85-4efc-9a9d-fbb61a43ebac" xlink:to="loc_us-gaap_DividendsCash_04139d81-3619-43e0-8619-319cc001f404" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_72d73186-8290-4f5c-bf02-deb8325905f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a5e95e45-d51e-478f-ae62-23feaf49d6fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_373f62d9-d659-4e08-8d6d-950e7f546004" xlink:to="loc_us-gaap_StatementTable_a5e95e45-d51e-478f-ae62-23feaf49d6fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8488d4bb-e048-41a0-9279-261dc23d51cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a5e95e45-d51e-478f-ae62-23feaf49d6fa" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8488d4bb-e048-41a0-9279-261dc23d51cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8488d4bb-e048-41a0-9279-261dc23d51cf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8488d4bb-e048-41a0-9279-261dc23d51cf" xlink:to="loc_us-gaap_ClassOfStockDomain_8488d4bb-e048-41a0-9279-261dc23d51cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0e328c80-901d-4353-9bb0-faa446477feb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8488d4bb-e048-41a0-9279-261dc23d51cf" xlink:to="loc_us-gaap_ClassOfStockDomain_0e328c80-901d-4353-9bb0-faa446477feb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_7db042f6-c03a-4a02-a13e-2eea57cdde90" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0e328c80-901d-4353-9bb0-faa446477feb" xlink:to="loc_sui_CommonOpUnitsMember_7db042f6-c03a-4a02-a13e-2eea57cdde90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_161d88bf-1d06-433a-a540-c9ad2a845c67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a5e95e45-d51e-478f-ae62-23feaf49d6fa" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_161d88bf-1d06-433a-a540-c9ad2a845c67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_161d88bf-1d06-433a-a540-c9ad2a845c67_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_161d88bf-1d06-433a-a540-c9ad2a845c67" xlink:to="loc_us-gaap_EquityComponentDomain_161d88bf-1d06-433a-a540-c9ad2a845c67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_161d88bf-1d06-433a-a540-c9ad2a845c67" xlink:to="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityMember_7e8974e7-606c-463b-90d1-9cbc0b52630c" xlink:href="sui-20210331.xsd#sui_TemporaryEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_sui_TemporaryEquityMember_7e8974e7-606c-463b-90d1-9cbc0b52630c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7755fb51-c275-4969-b249-1ed34ddd7401" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_CommonStockMember_7755fb51-c275-4969-b249-1ed34ddd7401" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_bfe589b6-07f6-4420-b545-14c706500159" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_bfe589b6-07f6-4420-b545-14c706500159" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember_5b71fb4c-46cc-48f0-9676-f284fb9ce70b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_AccumulatedDistributionsInExcessOfNetIncomeMember_5b71fb4c-46cc-48f0-9676-f284fb9ce70b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_3a9b5b91-4a09-42e2-bead-c80cc75fb753" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_3a9b5b91-4a09-42e2-bead-c80cc75fb753" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_902d687d-79bd-4c00-a92a-a5f6ea93b0ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_NoncontrollingInterestMember_902d687d-79bd-4c00-a92a-a5f6ea93b0ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_7cd4d352-3dc8-48b3-82da-c606954e2fd6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_ParentMember_7cd4d352-3dc8-48b3-82da-c606954e2fd6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMember_bed547be-4fbe-4339-8b61-56320cf73d19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_65eb524d-3150-4b32-818e-c92a8049ea27" xlink:to="loc_us-gaap_EquityMember_bed547be-4fbe-4339-8b61-56320cf73d19" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/BasisofPresentation" xlink:type="simple" xlink:href="sui-20210331.xsd#BasisofPresentation"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/BasisofPresentation" xlink:type="extended" id="ia8f320635917448c898c3055ddcde414_BasisofPresentation"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/BasisofPresentationBasisofPresentationDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#BasisofPresentationBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/BasisofPresentationBasisofPresentationDetails" xlink:type="extended" id="i4ea8b7d1f47b44b6951aa2b7712355db_BasisofPresentationBasisofPresentationDetails"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/Revenue" xlink:type="simple" xlink:href="sui-20210331.xsd#Revenue"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/Revenue" xlink:type="extended" id="ie77c3c4eb14642c2af12bb782b5b364b_Revenue"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RevenueTables" xlink:type="simple" xlink:href="sui-20210331.xsd#RevenueTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RevenueTables" xlink:type="extended" id="ida749eebc812474e850fd152932673f8_RevenueTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RevenueDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RevenueDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RevenueDetails" xlink:type="extended" id="i90dd833127884493aee38df1ac8bd229_RevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_54e47c45-a755-475f-9bda-d227e15a384a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_54e47c45-a755-475f-9bda-d227e15a384a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_c7cfc7c7-5c32-4cd4-92ae-98023e2d3415" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:to="loc_us-gaap_Revenues_c7cfc7c7-5c32-4cd4-92ae-98023e2d3415" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_3f56faea-e0c8-4670-af38-1e154ca55eaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:to="loc_us-gaap_NumberOfOperatingSegments_3f56faea-e0c8-4670-af38-1e154ca55eaf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_32ea6da5-71f8-4a9e-959a-89c7d4775303" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:to="loc_us-gaap_NumberOfReportableSegments_32ea6da5-71f8-4a9e-959a-89c7d4775303" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_520ce7f1-367a-460f-ab19-fb369d09cded" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e6c7fd2c-9c15-4b42-ba8d-6687ab3cc513" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_520ce7f1-367a-460f-ab19-fb369d09cded" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8837d14d-65f8-453b-9553-3283767f9227" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_520ce7f1-367a-460f-ab19-fb369d09cded" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8837d14d-65f8-453b-9553-3283767f9227" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8837d14d-65f8-453b-9553-3283767f9227_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8837d14d-65f8-453b-9553-3283767f9227" xlink:to="loc_us-gaap_SegmentDomain_8837d14d-65f8-453b-9553-3283767f9227_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8837d14d-65f8-453b-9553-3283767f9227" xlink:to="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RealPropertyOperationsSegmentMember_c2ce5532-c368-4632-8378-d9130afbf980" xlink:href="sui-20210331.xsd#sui_RealPropertyOperationsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:to="loc_sui_RealPropertyOperationsSegmentMember_c2ce5532-c368-4632-8378-d9130afbf980" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HomeSalesAndHomeRentalsSegmentMember_78317a36-0c26-438a-a133-a359441b8426" xlink:href="sui-20210331.xsd#sui_HomeSalesAndHomeRentalsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:to="loc_sui_HomeSalesAndHomeRentalsSegmentMember_78317a36-0c26-438a-a133-a359441b8426" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarinasMember_fa7f93d6-6043-4893-85db-92ab2c92dc55" xlink:href="sui-20210331.xsd#sui_MarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:to="loc_sui_MarinasMember_fa7f93d6-6043-4893-85db-92ab2c92dc55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MHMember_3bb7546f-550e-441d-8b82-e213e654650c" xlink:href="sui-20210331.xsd#sui_MHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:to="loc_sui_MHMember_3bb7546f-550e-441d-8b82-e213e654650c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RVMember_0ddfc93f-85a6-460f-98ba-ab588f6d43cd" xlink:href="sui-20210331.xsd#sui_RVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_709b919f-3ca3-417c-9fb2-50a54a476e7a" xlink:to="loc_sui_RVMember_0ddfc93f-85a6-460f-98ba-ab588f6d43cd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_49864367-28eb-418a-96d7-794bcdd579b3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_520ce7f1-367a-460f-ab19-fb369d09cded" xlink:to="loc_srt_ProductOrServiceAxis_49864367-28eb-418a-96d7-794bcdd579b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_49864367-28eb-418a-96d7-794bcdd579b3_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_49864367-28eb-418a-96d7-794bcdd579b3" xlink:to="loc_srt_ProductsAndServicesDomain_49864367-28eb-418a-96d7-794bcdd579b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_49864367-28eb-418a-96d7-794bcdd579b3" xlink:to="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_IncomeFromRealPropertyMember_099b2f11-a8af-41aa-96ee-3dc4d7bc2055" xlink:href="sui-20210331.xsd#sui_IncomeFromRealPropertyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_IncomeFromRealPropertyMember_099b2f11-a8af-41aa-96ee-3dc4d7bc2055" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RevenueFromHomeSalesMember_2bbbbbd3-16a4-4efd-af37-894feb34aaf6" xlink:href="sui-20210331.xsd#sui_RevenueFromHomeSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_RevenueFromHomeSalesMember_2bbbbbd3-16a4-4efd-af37-894feb34aaf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RentalHomeRevenueMember_4ac533cc-7257-42de-ba66-80c4002b1783" xlink:href="sui-20210331.xsd#sui_RentalHomeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_RentalHomeRevenueMember_4ac533cc-7257-42de-ba66-80c4002b1783" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AncillaryRevenuesMember_6d5151b7-6761-4926-9b45-93b18fc7a6a1" xlink:href="sui-20210331.xsd#sui_AncillaryRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_AncillaryRevenuesMember_6d5151b7-6761-4926-9b45-93b18fc7a6a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InterestMember_f8d09413-3e54-44db-af06-4c45d0802ae5" xlink:href="sui-20210331.xsd#sui_InterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_InterestMember_f8d09413-3e54-44db-af06-4c45d0802ae5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BrokerageCommissionsAndOtherRevenuesNetMember_7ceeddc6-9aa7-4984-8376-6a94ea018749" xlink:href="sui-20210331.xsd#sui_BrokerageCommissionsAndOtherRevenuesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7c9cc08f-0802-4a77-ba7f-7a4cfcdd920a" xlink:to="loc_sui_BrokerageCommissionsAndOtherRevenuesNetMember_7ceeddc6-9aa7-4984-8376-6a94ea018749" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RevenueContractBalancesDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RevenueContractBalancesDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RevenueContractBalancesDetails" xlink:type="extended" id="if14ff1aab12c44159a1360c3fb1686f9_RevenueContractBalancesDetails"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitions" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitions"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitions" xlink:type="extended" id="ie8603b7095794e0c82caa3f1b284288e_RealEstateAcquisitions"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitionsTables" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitionsTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitionsTables" xlink:type="extended" id="i8420f6b10d314a49837d4755300aec79_RealEstateAcquisitionsTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitionsScheduleofBusinessAcquisitionsbyAcquisitionDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitionsScheduleofBusinessAcquisitionsbyAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitionsScheduleofBusinessAcquisitionsbyAcquisitionDetails" xlink:type="extended" id="i3ecc9f8c639d48128a882c3a207980e7_RealEstateAcquisitionsScheduleofBusinessAcquisitionsbyAcquisitionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofUnitsinRealEstatePropertyDevelopmentSites_1bf6c7e3-8e81-4c58-9497-f051d5b0e956" xlink:href="sui-20210331.xsd#sui_NumberofUnitsinRealEstatePropertyDevelopmentSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberofUnitsinRealEstatePropertyDevelopmentSites_1bf6c7e3-8e81-4c58-9497-f051d5b0e956" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_b2484af8-0a47-4dd9-a432-5bb34be099b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_b2484af8-0a47-4dd9-a432-5bb34be099b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofMotorHomeCommunities_f6e353b2-bddf-4680-b51a-4a97aff0b10d" xlink:href="sui-20210331.xsd#sui_NumberofMotorHomeCommunities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberofMotorHomeCommunities_f6e353b2-bddf-4680-b51a-4a97aff0b10d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_cbada932-d1fd-4fca-af4d-f7d4e4f0ac0c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_cbada932-d1fd-4fca-af4d-f7d4e4f0ac0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofMHSites_42c21df8-e081-4eae-92c4-dc8ace3aac28" xlink:href="sui-20210331.xsd#sui_NumberofMHSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberofMHSites_42c21df8-e081-4eae-92c4-dc8ace3aac28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofRVSites_7f80728d-8747-49b9-8f31-4484d7e39915" xlink:href="sui-20210331.xsd#sui_NumberofRVSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberofRVSites_7f80728d-8747-49b9-8f31-4484d7e39915" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_4692f648-f05d-40ed-b33b-c4f986a9cd19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_4692f648-f05d-40ed-b33b-c4f986a9cd19" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfMarinasOwned_2f9ca95f-1a9f-40f7-894a-179de52ae04c" xlink:href="sui-20210331.xsd#sui_NumberOfMarinasOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberOfMarinasOwned_2f9ca95f-1a9f-40f7-894a-179de52ae04c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfCommunitiesImpaired_62e6c690-c0a3-4c10-9844-f1da04638ca6" xlink:href="sui-20210331.xsd#sui_NumberOfCommunitiesImpaired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_NumberOfCommunitiesImpaired_62e6c690-c0a3-4c10-9844-f1da04638ca6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_cbff4800-42b0-42e2-9d79-1ab03505564a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_cbff4800-42b0-42e2-9d79-1ab03505564a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_a2705298-a6e0-468b-8f1f-9a85e7bd264c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_a2705298-a6e0-468b-8f1f-9a85e7bd264c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_0c95faf7-7ec2-4265-84c1-11fe7422d72b" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_0c95faf7-7ec2-4265-84c1-11fe7422d72b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities_a7a97802-01d9-42a8-8eb0-a6badeb2513d" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities_a7a97802-01d9-42a8-8eb0-a6badeb2513d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_2ed608d1-fa0a-455a-b0ce-343a9c9875dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_2ed608d1-fa0a-455a-b0ce-343a9c9875dc" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_7d05bab0-c929-41ad-9f01-ba0b85c66a6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_7d05bab0-c929-41ad-9f01-ba0b85c66a6e" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_1ec4788c-6f9b-4f80-be0a-12fe46df2b5e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_1ec4788c-6f9b-4f80-be0a-12fe46df2b5e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_65454aca-ef12-4d65-941c-eaa64d4b5420" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_65454aca-ef12-4d65-941c-eaa64d4b5420" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_cbd0188a-7a35-4464-ac7d-63e93c282b15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_cbd0188a-7a35-4464-ac7d-63e93c282b15" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationConsideredTransferredDeferredPayment_b9b54124-762a-4cad-8cf2-8618164f3e5e" xlink:href="sui-20210331.xsd#sui_BusinessCombinationConsideredTransferredDeferredPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_BusinessCombinationConsideredTransferredDeferredPayment_b9b54124-762a-4cad-8cf2-8618164f3e5e" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionPaymentsToAcquireBusinessesGross_4ce73afa-adca-44db-83ba-8a1c7f801242" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionPaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_AssetAcquisitionPaymentsToAcquireBusinessesGross_4ce73afa-adca-44db-83ba-8a1c7f801242" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles_4099a740-b702-4582-bae4-08493ff20789" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles_4099a740-b702-4582-bae4-08493ff20789" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_f55477e9-4452-44e4-976a-aa188152d027" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_f55477e9-4452-44e4-976a-aa188152d027" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_e5ac44b0-a34f-43f8-bbc4-fe573715bb41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_e5ac44b0-a34f-43f8-bbc4-fe573715bb41" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_c6fe31ff-09aa-4a7e-8dee-82b79d1429e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_c6fe31ff-09aa-4a7e-8dee-82b79d1429e0" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets_437af2c2-5edb-44bf-bee1-14ce2aef3b4b" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets_437af2c2-5edb-44bf-bee1-14ce2aef3b4b" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfUnitsInRealEstateProperty_5039dcd9-6cee-4b84-b4a6-38b45ba908ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfUnitsInRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_NumberOfUnitsInRealEstateProperty_5039dcd9-6cee-4b84-b4a6-38b45ba908ff" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5e2d33de-1c8d-43d7-bda6-f83b3ea35163" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_39a5f73a-84db-433d-a96e-21c037aed129" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5e2d33de-1c8d-43d7-bda6-f83b3ea35163" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5e2d33de-1c8d-43d7-bda6-f83b3ea35163" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_0efe02f8-d1fc-4cf7-9f5a-9d9880c2316d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CapeCodMember_a2966bce-3d72-4bb4-8949-f8020b2022b5" xlink:href="sui-20210331.xsd#sui_CapeCodMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_CapeCodMember_a2966bce-3d72-4bb4-8949-f8020b2022b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JellystoneNaturalBridgeMember_a1b6e90f-ba0f-49ba-88e9-f37f6b0d0f6b" xlink:href="sui-20210331.xsd#sui_JellystoneNaturalBridgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_JellystoneNaturalBridgeMember_a1b6e90f-ba0f-49ba-88e9-f37f6b0d0f6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ForestSpringsMember_436dcaf9-8402-4fe8-b0cb-89480f36adf2" xlink:href="sui-20210331.xsd#sui_ForestSpringsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_ForestSpringsMember_436dcaf9-8402-4fe8-b0cb-89480f36adf2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CrownVillaMember_c3474b7a-5b8b-4b66-800b-8a71acc67c04" xlink:href="sui-20210331.xsd#sui_CrownVillaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_CrownVillaMember_c3474b7a-5b8b-4b66-800b-8a71acc67c04" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FlamingoLakeMember_10713ff3-5e57-472d-b8e4-075f0cd01d69" xlink:href="sui-20210331.xsd#sui_FlamingoLakeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_FlamingoLakeMember_10713ff3-5e57-472d-b8e4-075f0cd01d69" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_WoodsmokeMember_5ce39dcd-4850-475f-8648-f26620f04ded" xlink:href="sui-20210331.xsd#sui_WoodsmokeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_WoodsmokeMember_5ce39dcd-4850-475f-8648-f26620f04ded" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JellystoneLoneStarMember_bbfa8394-3192-4771-b5d5-ee48cf4c1177" xlink:href="sui-20210331.xsd#sui_JellystoneLoneStarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_JellystoneLoneStarMember_bbfa8394-3192-4771-b5d5-ee48cf4c1177" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ElCapitanOceanMesaMember_dd00c9bb-5de2-4c52-8d0a-6be4b284319e" xlink:href="sui-20210331.xsd#sui_ElCapitanOceanMesaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_ElCapitanOceanMesaMember_dd00c9bb-5de2-4c52-8d0a-6be4b284319e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HighlandGreenEstatesTroyVillaMember_5d46cc51-60c5-4532-97fb-30feca985106" xlink:href="sui-20210331.xsd#sui_HighlandGreenEstatesTroyVillaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_HighlandGreenEstatesTroyVillaMember_5d46cc51-60c5-4532-97fb-30feca985106" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SlickRockMember_a17d0bba-87d5-4763-9418-6230486709bf" xlink:href="sui-20210331.xsd#sui_SlickRockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SlickRockMember_a17d0bba-87d5-4763-9418-6230486709bf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PandionRidgeMember_f495d7cb-e67e-4ed5-aa3f-43dbaad17424" xlink:href="sui-20210331.xsd#sui_PandionRidgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_PandionRidgeMember_f495d7cb-e67e-4ed5-aa3f-43dbaad17424" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JensenPropertyAcquisitionMember_465ccbb8-0d93-4966-b610-4c5be59161ee" xlink:href="sui-20210331.xsd#sui_JensenPropertyAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_JensenPropertyAcquisitionMember_465ccbb8-0d93-4966-b610-4c5be59161ee" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GlenEllisMember_08d6066a-a10a-4f66-a65a-8b97ad8122ff" xlink:href="sui-20210331.xsd#sui_GlenEllisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_GlenEllisMember_08d6066a-a10a-4f66-a65a-8b97ad8122ff" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LeisurePointResortMember_ddff6ccd-fe54-4006-be6f-97e6e77c2ca0" xlink:href="sui-20210331.xsd#sui_LeisurePointResortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_LeisurePointResortMember_ddff6ccd-fe54-4006-be6f-97e6e77c2ca0" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ReunionLakeMember_28284a11-29f0-4ba7-a299-74274c0afad6" xlink:href="sui-20210331.xsd#sui_ReunionLakeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_ReunionLakeMember_28284a11-29f0-4ba7-a299-74274c0afad6" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RiverPlantationMember_ec8e15f2-4570-4d88-ae88-774a1446f172" xlink:href="sui-20210331.xsd#sui_RiverPlantationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_RiverPlantationMember_ec8e15f2-4570-4d88-ae88-774a1446f172" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MasseysLandingMember_84217fbd-c742-4e7f-b2bf-df955f7ed5ae" xlink:href="sui-20210331.xsd#sui_MasseysLandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_MasseysLandingMember_84217fbd-c742-4e7f-b2bf-df955f7ed5ae" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ShelbyPropertiesMember_9cd5c909-4514-4aa5-9228-1254e236da37" xlink:href="sui-20210331.xsd#sui_ShelbyPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_ShelbyPropertiesMember_9cd5c909-4514-4aa5-9228-1254e236da37" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BuenaVistaMember_2829affd-7126-49a2-828c-313ce7848282" xlink:href="sui-20210331.xsd#sui_BuenaVistaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_BuenaVistaMember_2829affd-7126-49a2-828c-313ce7848282" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CountryVillageMember_057eb98c-6ce2-47c2-b7fd-6a391053c66a" xlink:href="sui-20210331.xsd#sui_CountryVillageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_CountryVillageMember_057eb98c-6ce2-47c2-b7fd-6a391053c66a" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HidnPinesMember_f7d76027-d61f-41c6-a1ea-d6bdc9d098cf" xlink:href="sui-20210331.xsd#sui_HidnPinesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_HidnPinesMember_f7d76027-d61f-41c6-a1ea-d6bdc9d098cf" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HaciendadelRioMember_d09addb5-7997-42ba-871b-186de6d51a40" xlink:href="sui-20210331.xsd#sui_HaciendadelRioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_HaciendadelRioMember_d09addb5-7997-42ba-871b-186de6d51a40" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssociationIslandKOAMember_2af9ac44-c5f5-4e49-b3da-b8e5b9428fab" xlink:href="sui-20210331.xsd#sui_AssociationIslandKOAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_AssociationIslandKOAMember_2af9ac44-c5f5-4e49-b3da-b8e5b9428fab" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BlueWaterMember_b79eca97-8224-4d09-9d66-8abf5c8fd808" xlink:href="sui-20210331.xsd#sui_BlueWaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_BlueWaterMember_b79eca97-8224-4d09-9d66-8abf5c8fd808" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TranquilityMHCMember_7a20831e-51e9-4967-a812-b33380b92945" xlink:href="sui-20210331.xsd#sui_TranquilityMHCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_TranquilityMHCMember_7a20831e-51e9-4967-a812-b33380b92945" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PleasantBeachCampgroundMember_426f8d08-7a7e-4dad-9fa4-20230577b292" xlink:href="sui-20210331.xsd#sui_PleasantBeachCampgroundMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_PleasantBeachCampgroundMember_426f8d08-7a7e-4dad-9fa4-20230577b292" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CherrystoneFamilyCampingMember_94e822a1-4cf7-446d-ad82-99b126ca110f" xlink:href="sui-20210331.xsd#sui_CherrystoneFamilyCampingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_CherrystoneFamilyCampingMember_94e822a1-4cf7-446d-ad82-99b126ca110f" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BeachwoodMember_7a1aab84-bfa9-417a-8c95-621876187afb" xlink:href="sui-20210331.xsd#sui_BeachwoodMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_BeachwoodMember_7a1aab84-bfa9-417a-8c95-621876187afb" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasMember_01c6cfc1-1a6d-48f2-a13e-74d834b8c223" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborMarinasMember_01c6cfc1-1a6d-48f2-a13e-74d834b8c223" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_IslamoradaAndAnglerHouseMember_34a2f438-9c50-4ae8-9a95-97280c13b489" xlink:href="sui-20210331.xsd#sui_IslamoradaAndAnglerHouseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_IslamoradaAndAnglerHouseMember_34a2f438-9c50-4ae8-9a95-97280c13b489" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EdgartonMember_3e91f687-1d96-404a-a3d2-96f055bc3214" xlink:href="sui-20210331.xsd#sui_EdgartonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_EdgartonMember_3e91f687-1d96-404a-a3d2-96f055bc3214" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GigHarborMember_75f12746-2f14-4666-b839-340d8fbaf630" xlink:href="sui-20210331.xsd#sui_GigHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_GigHarborMember_75f12746-2f14-4666-b839-340d8fbaf630" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaineMHPortfolioMember_7f52364a-6af7-4da4-b1cd-24f0dd73c20e" xlink:href="sui-20210331.xsd#sui_MaineMHPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_MaineMHPortfolioMember_7f52364a-6af7-4da4-b1cd-24f0dd73c20e" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MouseMountainMember_f5096cce-4eff-4fbb-93dc-79ef1d66d7c4" xlink:href="sui-20210331.xsd#sui_MouseMountainMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_MouseMountainMember_f5096cce-4eff-4fbb-93dc-79ef1d66d7c4" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LakeviewMobileEstatesMember_828bd2da-670c-4b3c-aff6-f5a74cb8d691" xlink:href="sui-20210331.xsd#sui_LakeviewMobileEstatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_LakeviewMobileEstatesMember_828bd2da-670c-4b3c-aff6-f5a74cb8d691" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ShenandoahAcresMember_c3e5a83d-4cb7-48a1-8880-72eff4ff791b" xlink:href="sui-20210331.xsd#sui_ShenandoahAcresMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_ShenandoahAcresMember_c3e5a83d-4cb7-48a1-8880-72eff4ff791b" xlink:type="arc" order="35"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JellystoneAtBartonLakeMember_42ec2d07-41a7-4608-a4ba-da2633b447eb" xlink:href="sui-20210331.xsd#sui_JellystoneAtBartonLakeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_JellystoneAtBartonLakeMember_42ec2d07-41a7-4608-a4ba-da2633b447eb" xlink:type="arc" order="36"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_KittatinnyPortfolioMember_61b1013b-f71f-4ca3-87f0-fe41b8c1def7" xlink:href="sui-20210331.xsd#sui_KittatinnyPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_KittatinnyPortfolioMember_61b1013b-f71f-4ca3-87f0-fe41b8c1def7" xlink:type="arc" order="37"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborHideawayBayMember_f5173421-49fd-44bc-9219-de9dcf38b5e8" xlink:href="sui-20210331.xsd#sui_SafeHarborHideawayBayMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborHideawayBayMember_f5173421-49fd-44bc-9219-de9dcf38b5e8" xlink:type="arc" order="38"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborAnacapaIsleMember_9f9640f1-4df2-46d9-a7b5-cc1fc1adba54" xlink:href="sui-20210331.xsd#sui_SafeHarborAnacapaIsleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborAnacapaIsleMember_9f9640f1-4df2-46d9-a7b5-cc1fc1adba54" xlink:type="arc" order="39"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborRybovichPortfolioMember_baca907c-6121-404a-b23b-7b5b53b201cb" xlink:href="sui-20210331.xsd#sui_SafeHarborRybovichPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborRybovichPortfolioMember_baca907c-6121-404a-b23b-7b5b53b201cb" xlink:type="arc" order="40"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrimeMarthasVineyardMember_72ef7150-56ad-4374-8453-44a20698cb18" xlink:href="sui-20210331.xsd#sui_PrimeMarthasVineyardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_PrimeMarthasVineyardMember_72ef7150-56ad-4374-8453-44a20698cb18" xlink:type="arc" order="41"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborAnnapolisMember_5abfd3a6-6f30-4c03-8f3d-a3d9d06d6e44" xlink:href="sui-20210331.xsd#sui_SafeHarborAnnapolisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborAnnapolisMember_5abfd3a6-6f30-4c03-8f3d-a3d9d06d6e44" xlink:type="arc" order="42"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborWickfordCoveMember_f0aa7539-439d-4f39-a862-93434e2bab7d" xlink:href="sui-20210331.xsd#sui_SafeHarborWickfordCoveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborWickfordCoveMember_f0aa7539-439d-4f39-a862-93434e2bab7d" xlink:type="arc" order="43"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborRocklandMember_5050ce75-35e1-459e-99b1-4cb36f0339e3" xlink:href="sui-20210331.xsd#sui_SafeHarborRocklandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborRocklandMember_5050ce75-35e1-459e-99b1-4cb36f0339e3" xlink:type="arc" order="44"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMearsAnnapolisMember_0e3dca96-ff3f-4118-bbe3-e9d62e2e8c2f" xlink:href="sui-20210331.xsd#sui_SafeHarborMearsAnnapolisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bf78c468-b276-46e5-8fcb-5939224a5653" xlink:to="loc_sui_SafeHarborMearsAnnapolisMember_0e3dca96-ff3f-4118-bbe3-e9d62e2e8c2f" xlink:type="arc" order="45"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5e2d33de-1c8d-43d7-bda6-f83b3ea35163" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1" xlink:to="loc_us-gaap_ClassOfStockDomain_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0a7bec86-8a13-4c99-b1f1-b6ae03203ca1" xlink:to="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesEPreferredOPUnitsDomain_656e07c6-12a5-4487-8058-28aedb276a9b" xlink:href="sui-20210331.xsd#sui_SeriesEPreferredOPUnitsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_SeriesEPreferredOPUnitsDomain_656e07c6-12a5-4487-8058-28aedb276a9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_cf857daf-67fa-495b-87ef-032d4cff4749" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_cf857daf-67fa-495b-87ef-032d4cff4749" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_0090f70b-7699-475b-b0d8-c90d62191eb3" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_CommonOpUnitsMember_0090f70b-7699-475b-b0d8-c90d62191eb3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesGPreferredOPUnitsMember_db6c215f-155b-4bff-96d2-da5713308578" xlink:href="sui-20210331.xsd#sui_SeriesGPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_SeriesGPreferredOPUnitsMember_db6c215f-155b-4bff-96d2-da5713308578" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesHPreferredOPUnitsMember_486ad031-8cfe-44b6-9a6d-88b8f8e85e5b" xlink:href="sui-20210331.xsd#sui_SeriesHPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_SeriesHPreferredOPUnitsMember_486ad031-8cfe-44b6-9a6d-88b8f8e85e5b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesIPreferredOPUnitsMember_1a0879ff-911c-4f4d-9611-3b5b58c8de2c" xlink:href="sui-20210331.xsd#sui_SeriesIPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d58f383b-e398-431e-8306-9b4669afeb4c" xlink:to="loc_sui_SeriesIPreferredOPUnitsMember_1a0879ff-911c-4f4d-9611-3b5b58c8de2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionAxis_c0bd4d24-4a33-450a-b293-b89d183a35e7" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5e2d33de-1c8d-43d7-bda6-f83b3ea35163" xlink:to="loc_sui_AssetAcquisitionAxis_c0bd4d24-4a33-450a-b293-b89d183a35e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_c0bd4d24-4a33-450a-b293-b89d183a35e7_default" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_AssetAcquisitionAxis_c0bd4d24-4a33-450a-b293-b89d183a35e7" xlink:to="loc_sui_AssetAcquisitionDomain_c0bd4d24-4a33-450a-b293-b89d183a35e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_7cfe7255-6509-4a98-99d2-9a1c1d87ded4" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_AssetAcquisitionAxis_c0bd4d24-4a33-450a-b293-b89d183a35e7" xlink:to="loc_sui_AssetAcquisitionDomain_7cfe7255-6509-4a98-99d2-9a1c1d87ded4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborAnnapolisMember_76acd0fb-932d-4046-bcb3-abf23dadebfe" xlink:href="sui-20210331.xsd#sui_SafeHarborAnnapolisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_7cfe7255-6509-4a98-99d2-9a1c1d87ded4" xlink:to="loc_sui_SafeHarborAnnapolisMember_76acd0fb-932d-4046-bcb3-abf23dadebfe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborWickfordCoveMember_19d3041a-f212-43d6-bf7d-885413ff50dd" xlink:href="sui-20210331.xsd#sui_SafeHarborWickfordCoveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_7cfe7255-6509-4a98-99d2-9a1c1d87ded4" xlink:to="loc_sui_SafeHarborWickfordCoveMember_19d3041a-f212-43d6-bf7d-885413ff50dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborRocklandMember_3c36d646-e1e2-4ce1-beb8-00a7fbce9e53" xlink:href="sui-20210331.xsd#sui_SafeHarborRocklandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_7cfe7255-6509-4a98-99d2-9a1c1d87ded4" xlink:to="loc_sui_SafeHarborRocklandMember_3c36d646-e1e2-4ce1-beb8-00a7fbce9e53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMearsAnnapolisMember_15108c46-d5d5-49dd-876b-6205494b6f9c" xlink:href="sui-20210331.xsd#sui_SafeHarborMearsAnnapolisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_AssetAcquisitionAxis_c0bd4d24-4a33-450a-b293-b89d183a35e7" xlink:to="loc_sui_SafeHarborMearsAnnapolisMember_15108c46-d5d5-49dd-876b-6205494b6f9c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitionsScheduleofPurchasePriceAllocationDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitionsScheduleofPurchasePriceAllocationDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitionsScheduleofPurchasePriceAllocationDetails" xlink:type="extended" id="if7f0ec2d925448d2abcb9433e022d8e2_RealEstateAcquisitionsScheduleofPurchasePriceAllocationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_6427d2f9-00f3-4076-b5fc-3e29c7842419" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_1027601f-82d6-4746-9010-5b233ff29793" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6427d2f9-00f3-4076-b5fc-3e29c7842419" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_1027601f-82d6-4746-9010-5b233ff29793" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6427d2f9-00f3-4076-b5fc-3e29c7842419" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_4c0e5458-cb53-40aa-b5d0-b4472cda9a96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_4c0e5458-cb53-40aa-b5d0-b4472cda9a96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_10347f0d-911f-40dd-a24b-da3eb62afcf7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_10347f0d-911f-40dd-a24b-da3eb62afcf7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_cd4aea11-b245-4a19-a761-d0f2f2b5a49c" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_cd4aea11-b245-4a19-a761-d0f2f2b5a49c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities_8eb971e8-d787-4e6a-a51b-366032adbe7e" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherLiabilities_8eb971e8-d787-4e6a-a51b-366032adbe7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_82bf1405-7059-43f2-8571-a9634020d2cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_b0082852-75a5-4935-bb33-4ceedca45038" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_82bf1405-7059-43f2-8571-a9634020d2cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6427d2f9-00f3-4076-b5fc-3e29c7842419" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_006b9c18-3d84-4af9-819a-aef55735d1b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_006b9c18-3d84-4af9-819a-aef55735d1b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_aa0e53d6-263a-41bc-85be-b1e5d9d67a21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_aa0e53d6-263a-41bc-85be-b1e5d9d67a21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_86f1d885-e86b-4ac5-aadf-56b3822bfa17" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_86f1d885-e86b-4ac5-aadf-56b3822bfa17" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_934918f0-5173-4d9c-8cdb-a28f05c47ecd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_934918f0-5173-4d9c-8cdb-a28f05c47ecd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_0f2114e5-6461-4a38-8934-9eb6962488fe" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_0f2114e5-6461-4a38-8934-9eb6962488fe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionConsiderationTransferred_6341f866-7d36-4cb9-bdd6-e19965439abb" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionConsiderationTransferred_6341f866-7d36-4cb9-bdd6-e19965439abb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_edd55599-dd57-410c-8c07-d8c812ca2330" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_edd55599-dd57-410c-8c07-d8c812ca2330" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_5b3c7836-61b3-4de3-a3f9-dc2aafd29f61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_5b3c7836-61b3-4de3-a3f9-dc2aafd29f61" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_97fd58cc-b0e8-4950-b747-86fe6238d035" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_97fd58cc-b0e8-4950-b747-86fe6238d035" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionConsiderationTransferredEquityInterestsIssuedAndIssuable_979552a1-b326-404b-84bf-ea0870fd4d45" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionConsiderationTransferredEquityInterestsIssuedAndIssuable_979552a1-b326-404b-84bf-ea0870fd4d45" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionPaymentsToAcquireBusinessesGross_e897e500-76f7-4d2f-84e9-bcf775620cb6" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionPaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionPaymentsToAcquireBusinessesGross_e897e500-76f7-4d2f-84e9-bcf775620cb6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsLiabilities_641d093b-0d4c-4b9f-8088-5a94f3eed5c9" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsLiabilities_641d093b-0d4c-4b9f-8088-5a94f3eed5c9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets_419d9351-a3f2-47d4-a3a6-0079d55ba17d" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesGoodwillAndOtherIntangibleAssets_419d9351-a3f2-47d4-a3a6-0079d55ba17d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_a7ab9c33-08da-45e3-ac28-08ace740bea0" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_a7ab9c33-08da-45e3-ac28-08ace740bea0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_2c065943-feab-4014-9a88-32e043e075cf" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsLiabilitiesInventory_2c065943-feab-4014-9a88-32e043e075cf" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles_ff2d23d5-14f5-4782-947c-5122a60d5a77" xlink:href="sui-20210331.xsd#sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndOtherIntangibles_ff2d23d5-14f5-4782-947c-5122a60d5a77" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfMarinasOwned_8fa8c275-7349-4cff-91da-ae44c915b0ee" xlink:href="sui-20210331.xsd#sui_NumberOfMarinasOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_7deb7371-2afc-4d2b-87e7-0f793aa92b6f" xlink:to="loc_sui_NumberOfMarinasOwned_8fa8c275-7349-4cff-91da-ae44c915b0ee" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_94bd9ab5-adc4-4b7f-ba7a-ca87cc2a9e2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6427d2f9-00f3-4076-b5fc-3e29c7842419" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_94bd9ab5-adc4-4b7f-ba7a-ca87cc2a9e2f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_f45735c3-df81-4f13-b869-c3375b8024bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_94bd9ab5-adc4-4b7f-ba7a-ca87cc2a9e2f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_f45735c3-df81-4f13-b869-c3375b8024bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f45735c3-df81-4f13-b869-c3375b8024bf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f45735c3-df81-4f13-b869-c3375b8024bf" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f45735c3-df81-4f13-b869-c3375b8024bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f45735c3-df81-4f13-b869-c3375b8024bf" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CapeCodMember_5d2bb9c9-e24c-4e9d-ba91-592fa28e50b6" xlink:href="sui-20210331.xsd#sui_CapeCodMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_CapeCodMember_5d2bb9c9-e24c-4e9d-ba91-592fa28e50b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JellystoneNaturalBridgeMember_755c53d6-2ce0-4d23-870a-fa3ac0befd8e" xlink:href="sui-20210331.xsd#sui_JellystoneNaturalBridgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_JellystoneNaturalBridgeMember_755c53d6-2ce0-4d23-870a-fa3ac0befd8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ForestSpringsMember_60a4be63-fc0d-4f03-a2ae-429e62fb97df" xlink:href="sui-20210331.xsd#sui_ForestSpringsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_ForestSpringsMember_60a4be63-fc0d-4f03-a2ae-429e62fb97df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CrownVillaMember_c5bda9c5-07fe-444a-a142-114d0705ff6c" xlink:href="sui-20210331.xsd#sui_CrownVillaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_CrownVillaMember_c5bda9c5-07fe-444a-a142-114d0705ff6c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FlamingoLakeMember_0f9e15a8-77ca-4fb9-810e-77d2a22c3b67" xlink:href="sui-20210331.xsd#sui_FlamingoLakeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_FlamingoLakeMember_0f9e15a8-77ca-4fb9-810e-77d2a22c3b67" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_WoodsmokeMember_c54b83da-dcc6-4a79-b879-a119bc4e8a21" xlink:href="sui-20210331.xsd#sui_WoodsmokeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_WoodsmokeMember_c54b83da-dcc6-4a79-b879-a119bc4e8a21" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JellystoneLoneStarMember_44fdbb64-4594-4879-9f37-9d4565b02a22" xlink:href="sui-20210331.xsd#sui_JellystoneLoneStarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_JellystoneLoneStarMember_44fdbb64-4594-4879-9f37-9d4565b02a22" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ElCapitanOceanMesaMember_0eeaa377-a315-40ee-92c3-3615994bbbe6" xlink:href="sui-20210331.xsd#sui_ElCapitanOceanMesaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_ElCapitanOceanMesaMember_0eeaa377-a315-40ee-92c3-3615994bbbe6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HighlandGreenEstatesTroyVillaMember_3fba9f2b-de61-4b9c-8193-a86da062121f" xlink:href="sui-20210331.xsd#sui_HighlandGreenEstatesTroyVillaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_HighlandGreenEstatesTroyVillaMember_3fba9f2b-de61-4b9c-8193-a86da062121f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SlickRockMember_6f95e9da-a714-4783-a95e-d225ddd910be" xlink:href="sui-20210331.xsd#sui_SlickRockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_SlickRockMember_6f95e9da-a714-4783-a95e-d225ddd910be" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PandionRidgeMember_3b140949-89c8-4538-8317-7b77af6f5cae" xlink:href="sui-20210331.xsd#sui_PandionRidgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_PandionRidgeMember_3b140949-89c8-4538-8317-7b77af6f5cae" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JensenPropertyAcquisitionMember_e7db5b64-905e-4af8-997f-d6d763048407" xlink:href="sui-20210331.xsd#sui_JensenPropertyAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_JensenPropertyAcquisitionMember_e7db5b64-905e-4af8-997f-d6d763048407" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GlenEllisMember_0425388e-0c00-4ffe-93c4-a8e754123db8" xlink:href="sui-20210331.xsd#sui_GlenEllisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_GlenEllisMember_0425388e-0c00-4ffe-93c4-a8e754123db8" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LeisurePointResortMember_5da90fdb-9d9e-4fe0-a80e-f737efb81ce1" xlink:href="sui-20210331.xsd#sui_LeisurePointResortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_LeisurePointResortMember_5da90fdb-9d9e-4fe0-a80e-f737efb81ce1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ReunionLakeMember_c544be35-af8a-4c3a-a64f-c1db12740c37" xlink:href="sui-20210331.xsd#sui_ReunionLakeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_ReunionLakeMember_c544be35-af8a-4c3a-a64f-c1db12740c37" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RiverPlantationMember_2d0e0059-6d92-4357-a229-1c34211ad1cc" xlink:href="sui-20210331.xsd#sui_RiverPlantationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_RiverPlantationMember_2d0e0059-6d92-4357-a229-1c34211ad1cc" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MasseysLandingMember_4e2b0a48-099b-4f94-952c-1838af2a4a9c" xlink:href="sui-20210331.xsd#sui_MasseysLandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_MasseysLandingMember_4e2b0a48-099b-4f94-952c-1838af2a4a9c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ShelbyPropertiesMember_6ec856e4-8366-4c08-acf5-9bc0fb3a3fd2" xlink:href="sui-20210331.xsd#sui_ShelbyPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_ShelbyPropertiesMember_6ec856e4-8366-4c08-acf5-9bc0fb3a3fd2" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BuenaVistaMember_ac59a038-f6d9-412e-a93d-dd252efa1565" xlink:href="sui-20210331.xsd#sui_BuenaVistaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_BuenaVistaMember_ac59a038-f6d9-412e-a93d-dd252efa1565" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CountryVillageMember_cc8e2de0-c3df-42bb-8d85-03ba9f446baf" xlink:href="sui-20210331.xsd#sui_CountryVillageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_CountryVillageMember_cc8e2de0-c3df-42bb-8d85-03ba9f446baf" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HidnPinesMember_33cd43ac-6ded-4356-a9f9-2ea35c20105c" xlink:href="sui-20210331.xsd#sui_HidnPinesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_HidnPinesMember_33cd43ac-6ded-4356-a9f9-2ea35c20105c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HaciendadelRioMember_2f9d1365-c0f9-40a0-a18c-0957bcc4c139" xlink:href="sui-20210331.xsd#sui_HaciendadelRioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_HaciendadelRioMember_2f9d1365-c0f9-40a0-a18c-0957bcc4c139" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssociationIslandKOAMember_75080e82-2d3c-4097-a384-83a3cdae4ffc" xlink:href="sui-20210331.xsd#sui_AssociationIslandKOAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_AssociationIslandKOAMember_75080e82-2d3c-4097-a384-83a3cdae4ffc" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BlueWaterMember_bf1dc1f2-97ba-494c-972a-ac2c62aaba9b" xlink:href="sui-20210331.xsd#sui_BlueWaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_BlueWaterMember_bf1dc1f2-97ba-494c-972a-ac2c62aaba9b" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TranquilityMHCMember_0557fb69-9d82-4e78-acb3-22a499d17ec4" xlink:href="sui-20210331.xsd#sui_TranquilityMHCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_TranquilityMHCMember_0557fb69-9d82-4e78-acb3-22a499d17ec4" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PleasantBeachCampgroundMember_272dea99-e480-4c66-bddf-17e2ae938f7e" xlink:href="sui-20210331.xsd#sui_PleasantBeachCampgroundMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_PleasantBeachCampgroundMember_272dea99-e480-4c66-bddf-17e2ae938f7e" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CherrystoneFamilyCampingMember_65b302df-e1b3-4dbf-a496-1a1282f12d18" xlink:href="sui-20210331.xsd#sui_CherrystoneFamilyCampingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_CherrystoneFamilyCampingMember_65b302df-e1b3-4dbf-a496-1a1282f12d18" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BeachwoodMember_94099b18-d36c-4489-9097-70007d999607" xlink:href="sui-20210331.xsd#sui_BeachwoodMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_BeachwoodMember_94099b18-d36c-4489-9097-70007d999607" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GigHarborMember_04846b36-156f-4d74-a8ad-fa68ebdc25e6" xlink:href="sui-20210331.xsd#sui_GigHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_GigHarborMember_04846b36-156f-4d74-a8ad-fa68ebdc25e6" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasMember_5a059251-37a6-4c24-b6fe-d46319941347" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_SafeHarborMarinasMember_5a059251-37a6-4c24-b6fe-d46319941347" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborHideawayBayMember_871a7151-a7d2-4eda-8baa-847347d8de35" xlink:href="sui-20210331.xsd#sui_SafeHarborHideawayBayMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_SafeHarborHideawayBayMember_871a7151-a7d2-4eda-8baa-847347d8de35" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborAnacapaIsleMember_caeef0a0-e856-4239-8a1d-49c104a6da89" xlink:href="sui-20210331.xsd#sui_SafeHarborAnacapaIsleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_SafeHarborAnacapaIsleMember_caeef0a0-e856-4239-8a1d-49c104a6da89" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborRybovichPortfolioMember_a5860b8e-a734-4b10-b524-9beeb3f72945" xlink:href="sui-20210331.xsd#sui_SafeHarborRybovichPortfolioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_SafeHarborRybovichPortfolioMember_a5860b8e-a734-4b10-b524-9beeb3f72945" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_IslamoradaAndAnglerHouseMember_96e0b7cb-11bf-4c64-9f5d-a48df187edaf" xlink:href="sui-20210331.xsd#sui_IslamoradaAndAnglerHouseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_IslamoradaAndAnglerHouseMember_96e0b7cb-11bf-4c64-9f5d-a48df187edaf" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrimeMarthasVineyardMember_309f5fed-0876-49d9-bf7a-1f7f7bc3b37d" xlink:href="sui-20210331.xsd#sui_PrimeMarthasVineyardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8c8f3b36-b896-42ae-8d67-e43a3061ebdf" xlink:to="loc_sui_PrimeMarthasVineyardMember_309f5fed-0876-49d9-bf7a-1f7f7bc3b37d" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionAxis_867fc0e4-5a05-4176-92ac-f75ad32cf22b" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_94bd9ab5-adc4-4b7f-ba7a-ca87cc2a9e2f" xlink:to="loc_sui_AssetAcquisitionAxis_867fc0e4-5a05-4176-92ac-f75ad32cf22b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_867fc0e4-5a05-4176-92ac-f75ad32cf22b_default" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_AssetAcquisitionAxis_867fc0e4-5a05-4176-92ac-f75ad32cf22b" xlink:to="loc_sui_AssetAcquisitionDomain_867fc0e4-5a05-4176-92ac-f75ad32cf22b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_f9b87def-7873-49be-b0c9-585c547b4422" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_AssetAcquisitionAxis_867fc0e4-5a05-4176-92ac-f75ad32cf22b" xlink:to="loc_sui_AssetAcquisitionDomain_f9b87def-7873-49be-b0c9-585c547b4422" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_IslamoradaAndAnglerHouseMember_27e35d6b-d069-4116-b3ea-c2acb5fec451" xlink:href="sui-20210331.xsd#sui_IslamoradaAndAnglerHouseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_f9b87def-7873-49be-b0c9-585c547b4422" xlink:to="loc_sui_IslamoradaAndAnglerHouseMember_27e35d6b-d069-4116-b3ea-c2acb5fec451" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrimeMarthasVineyardMember_8d015174-6a09-423c-a5b1-f9b928f9fce7" xlink:href="sui-20210331.xsd#sui_PrimeMarthasVineyardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_f9b87def-7873-49be-b0c9-585c547b4422" xlink:to="loc_sui_PrimeMarthasVineyardMember_8d015174-6a09-423c-a5b1-f9b928f9fce7" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitionsProFormaDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitionsProFormaDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitionsProFormaDetails" xlink:type="extended" id="i209cded061244182acb0b87e6c744b96_RealEstateAcquisitionsProFormaDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7d74b2ca-e21a-4de2-a463-f06e42076cfa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7d74b2ca-e21a-4de2-a463-f06e42076cfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_f4e90a4d-6dfe-4fc1-92ce-1de600fc9d63" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_f4e90a4d-6dfe-4fc1-92ce-1de600fc9d63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_22e77520-d5c4-483d-a69c-f66692b70fba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_22e77520-d5c4-483d-a69c-f66692b70fba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_dbbf5069-5cfb-4326-9324-6e28e3a7e13d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_dbbf5069-5cfb-4326-9324-6e28e3a7e13d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50844236-34ad-4815-8131-2ceac7e366ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_6903d777-35e4-4fe9-b460-3307aeed5f13" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50844236-34ad-4815-8131-2ceac7e366ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_619d097f-c93c-427d-808f-1e99f445d997" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50844236-34ad-4815-8131-2ceac7e366ad" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_619d097f-c93c-427d-808f-1e99f445d997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_619d097f-c93c-427d-808f-1e99f445d997_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_619d097f-c93c-427d-808f-1e99f445d997" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_619d097f-c93c-427d-808f-1e99f445d997_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_83398801-8cbc-4e45-a6f3-564a5eb46c4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_619d097f-c93c-427d-808f-1e99f445d997" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_83398801-8cbc-4e45-a6f3-564a5eb46c4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Acquisitions2019Member_8299ae00-8f79-4acc-9fc0-fd5a8331a18c" xlink:href="sui-20210331.xsd#sui_Acquisitions2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_83398801-8cbc-4e45-a6f3-564a5eb46c4e" xlink:to="loc_sui_Acquisitions2019Member_8299ae00-8f79-4acc-9fc0-fd5a8331a18c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Acquisitions2020Member_cbb37b4c-e0f3-4bfe-86cf-b907e73261eb" xlink:href="sui-20210331.xsd#sui_Acquisitions2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_83398801-8cbc-4e45-a6f3-564a5eb46c4e" xlink:to="loc_sui_Acquisitions2020Member_cbb37b4c-e0f3-4bfe-86cf-b907e73261eb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RealEstateAcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#RealEstateAcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RealEstateAcquisitionsNarrativeDetails" xlink:type="extended" id="i9440812fc33841f599e49c7d406c7cf5_RealEstateAcquisitionsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_06460772-d97d-4325-8638-9027990b26fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_06460772-d97d-4325-8638-9027990b26fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfMarinasOwned_ccb2fb74-cbb6-4e0f-83a7-4923954657c6" xlink:href="sui-20210331.xsd#sui_NumberOfMarinasOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberOfMarinasOwned_ccb2fb74-cbb6-4e0f-83a7-4923954657c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfMarinasManaged_5153361f-5a06-43fe-9c40-2097fe9e0813" xlink:href="sui-20210331.xsd#sui_NumberOfMarinasManaged"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberOfMarinasManaged_5153361f-5a06-43fe-9c40-2097fe9e0813" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfWetSlipsAndMoorings_97abe3d1-0e3f-4340-bcc3-26dde6cb0746" xlink:href="sui-20210331.xsd#sui_NumberOfWetSlipsAndMoorings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberOfWetSlipsAndMoorings_97abe3d1-0e3f-4340-bcc3-26dde6cb0746" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfDryRacks_0c0632d0-2e34-4744-b156-b68490e851fe" xlink:href="sui-20210331.xsd#sui_NumberOfDryRacks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberOfDryRacks_0c0632d0-2e34-4744-b156-b68490e851fe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfStorageSpaces_0e7593c4-dbff-4b96-bb10-0ff2c06f3982" xlink:href="sui-20210331.xsd#sui_NumberOfStorageSpaces"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberOfStorageSpaces_0e7593c4-dbff-4b96-bb10-0ff2c06f3982" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOfAssetsAcquired_da061e93-acdd-4f95-ba04-564a19503e9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueOfAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_FairValueOfAssetsAcquired_da061e93-acdd-4f95-ba04-564a19503e9e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand_fbc16769-35ec-45dd-9490-6d7b0d1ce922" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLand_fbc16769-35ec-45dd-9490-6d7b0d1ce922" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PurchaseofTangibleProperty_96f81dd6-8986-488e-9a40-f18ce61438ab" xlink:href="sui-20210331.xsd#sui_PurchaseofTangibleProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_PurchaseofTangibleProperty_96f81dd6-8986-488e-9a40-f18ce61438ab" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofMHSites_334d14e0-1e40-4e20-a49d-2f85f0ac9d91" xlink:href="sui-20210331.xsd#sui_NumberofMHSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_sui_NumberofMHSites_334d14e0-1e40-4e20-a49d-2f85f0ac9d91" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_585bc6fa-fe31-4ac6-b094-d356ea4f1f97" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_585bc6fa-fe31-4ac6-b094-d356ea4f1f97" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfProperties_e90af7eb-3009-46f2-a246-83740ed4c812" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_GainLossOnSaleOfProperties_e90af7eb-3009-46f2-a246-83740ed4c812" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_b910ca38-fa20-4553-a248-bada57c66972" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_b910ca38-fa20-4553-a248-bada57c66972" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfStatesInWhichEntityOperates_78297bfd-b732-444c-b683-3953d07b731a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfStatesInWhichEntityOperates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_NumberOfStatesInWhichEntityOperates_78297bfd-b732-444c-b683-3953d07b731a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_180ba4ee-7384-4ede-b3b4-ae97e3c24e11" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_f7d3c3db-8363-45e3-848a-1df3e23bf473" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:to="loc_dei_LegalEntityAxis_f7d3c3db-8363-45e3-848a-1df3e23bf473" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_f7d3c3db-8363-45e3-848a-1df3e23bf473_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_f7d3c3db-8363-45e3-848a-1df3e23bf473" xlink:to="loc_dei_EntityDomain_f7d3c3db-8363-45e3-848a-1df3e23bf473_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_697f23ee-1c65-4690-a0fd-ab3ccd6eab4e" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_f7d3c3db-8363-45e3-848a-1df3e23bf473" xlink:to="loc_dei_EntityDomain_697f23ee-1c65-4690-a0fd-ab3ccd6eab4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ChincoteagueMember_6af60641-2ffd-4ca6-b1e2-2392bcc9bc22" xlink:href="sui-20210331.xsd#sui_ChincoteagueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_697f23ee-1c65-4690-a0fd-ab3ccd6eab4e" xlink:to="loc_sui_ChincoteagueMember_6af60641-2ffd-4ca6-b1e2-2392bcc9bc22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_StraffordMember_499bd523-715a-4a89-8c06-bacb23529f76" xlink:href="sui-20210331.xsd#sui_StraffordMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_697f23ee-1c65-4690-a0fd-ab3ccd6eab4e" xlink:to="loc_sui_StraffordMember_499bd523-715a-4a89-8c06-bacb23529f76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3caf7e12-eb83-410e-8056-aed54f72ad21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3caf7e12-eb83-410e-8056-aed54f72ad21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3caf7e12-eb83-410e-8056-aed54f72ad21_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3caf7e12-eb83-410e-8056-aed54f72ad21" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3caf7e12-eb83-410e-8056-aed54f72ad21_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b15082d7-8968-43f4-ac27-22a2926bb3ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3caf7e12-eb83-410e-8056-aed54f72ad21" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b15082d7-8968-43f4-ac27-22a2926bb3ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CountrysideVillageMember_abde2b69-8b94-400a-89ae-2c035f76083b" xlink:href="sui-20210331.xsd#sui_CountrysideVillageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b15082d7-8968-43f4-ac27-22a2926bb3ac" xlink:to="loc_sui_CountrysideVillageMember_abde2b69-8b94-400a-89ae-2c035f76083b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e6a627f3-036e-4a15-b9de-79856867619d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e6a627f3-036e-4a15-b9de-79856867619d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e6a627f3-036e-4a15-b9de-79856867619d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e6a627f3-036e-4a15-b9de-79856867619d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e6a627f3-036e-4a15-b9de-79856867619d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1346a1d4-2bc4-4ad5-9e3e-ca586bc5f04b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e6a627f3-036e-4a15-b9de-79856867619d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1346a1d4-2bc4-4ad5-9e3e-ca586bc5f04b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasMember_be2448f8-f500-4cd1-a60b-c3bcb7dec693" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1346a1d4-2bc4-4ad5-9e3e-ca586bc5f04b" xlink:to="loc_sui_SafeHarborMarinasMember_be2448f8-f500-4cd1-a60b-c3bcb7dec693" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasFourPropertiesMember_f077aad6-0a8d-4d6d-a2d8-f140493a344b" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasFourPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1346a1d4-2bc4-4ad5-9e3e-ca586bc5f04b" xlink:to="loc_sui_SafeHarborMarinasFourPropertiesMember_f077aad6-0a8d-4d6d-a2d8-f140493a344b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasElevenPropertiesMember_f28b137b-c23c-47f6-ab65-b4ca7d040932" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasElevenPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1346a1d4-2bc4-4ad5-9e3e-ca586bc5f04b" xlink:to="loc_sui_SafeHarborMarinasElevenPropertiesMember_f28b137b-c23c-47f6-ab65-b4ca7d040932" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc" xlink:to="loc_us-gaap_RelatedPartyDomain_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_fd3c14b3-bfc3-4654-bcec-e8fa048f87b5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_e947bf56-a1dc-4e3e-aacc-6b0caa3c6dcc" xlink:to="loc_us-gaap_RelatedPartyDomain_fd3c14b3-bfc3-4654-bcec-e8fa048f87b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasMember_32b7b6ad-7b65-4312-a1e9-e476834c7b18" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_fd3c14b3-bfc3-4654-bcec-e8fa048f87b5" xlink:to="loc_sui_SafeHarborMarinasMember_32b7b6ad-7b65-4312-a1e9-e476834c7b18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionAxis_0188737b-8d5f-4341-bd8e-5f58f340e51f" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_5c321239-6534-4e6d-984a-6b8c9de42638" xlink:to="loc_sui_AssetAcquisitionAxis_0188737b-8d5f-4341-bd8e-5f58f340e51f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_0188737b-8d5f-4341-bd8e-5f58f340e51f_default" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_AssetAcquisitionAxis_0188737b-8d5f-4341-bd8e-5f58f340e51f" xlink:to="loc_sui_AssetAcquisitionDomain_0188737b-8d5f-4341-bd8e-5f58f340e51f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_e9981bb8-04c4-4e86-bcb7-f88de5f3e6dc" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_AssetAcquisitionAxis_0188737b-8d5f-4341-bd8e-5f58f340e51f" xlink:to="loc_sui_AssetAcquisitionDomain_e9981bb8-04c4-4e86-bcb7-f88de5f3e6dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMarinasMember_bab12e2e-8bdb-4d7a-9f09-c27fd4aa59d3" xlink:href="sui-20210331.xsd#sui_SafeHarborMarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_e9981bb8-04c4-4e86-bcb7-f88de5f3e6dc" xlink:to="loc_sui_SafeHarborMarinasMember_bab12e2e-8bdb-4d7a-9f09-c27fd4aa59d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BusinessCombinationsAndAssetsAcquisitionsMember_cc2c73f9-1631-4a2b-9559-aef4836a6519" xlink:href="sui-20210331.xsd#sui_BusinessCombinationsAndAssetsAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_e9981bb8-04c4-4e86-bcb7-f88de5f3e6dc" xlink:to="loc_sui_BusinessCombinationsAndAssetsAcquisitionsMember_cc2c73f9-1631-4a2b-9559-aef4836a6519" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrimeMarthasVineyardMember_a2f0bc70-b449-425d-a260-5dd7f55e6d5f" xlink:href="sui-20210331.xsd#sui_PrimeMarthasVineyardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_e9981bb8-04c4-4e86-bcb7-f88de5f3e6dc" xlink:to="loc_sui_PrimeMarthasVineyardMember_a2f0bc70-b449-425d-a260-5dd7f55e6d5f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/NotesAndOtherReceivables" xlink:type="simple" xlink:href="sui-20210331.xsd#NotesAndOtherReceivables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/NotesAndOtherReceivables" xlink:type="extended" id="ib2616b7c9846493e8c6a23171af85046_NotesAndOtherReceivables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/NotesAndOtherReceivablesTables" xlink:type="simple" xlink:href="sui-20210331.xsd#NotesAndOtherReceivablesTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/NotesAndOtherReceivablesTables" xlink:type="extended" id="i8b5ee7224e09450099657458e9ce9c84_NotesAndOtherReceivablesTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/NotesandOtherReceivablesScheduleofnotesandotherreceivablesDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#NotesandOtherReceivablesScheduleofnotesandotherreceivablesDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/NotesandOtherReceivablesScheduleofnotesandotherreceivablesDetails" xlink:type="extended" id="i837ecc6d3f1741d3b43d5c3f6e4ee9d7_NotesandOtherReceivablesScheduleofnotesandotherreceivablesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e3af1920-2742-4a98-9adc-4252b2c73e15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsAndNotesReceivableNet_2f6043f1-e301-44cb-bb33-7a1a674ef30a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsAndNotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e3af1920-2742-4a98-9adc-4252b2c73e15" xlink:to="loc_us-gaap_AccountsAndNotesReceivableNet_2f6043f1-e301-44cb-bb33-7a1a674ef30a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_a66cb735-fe29-4120-a522-7012efc71841" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e3af1920-2742-4a98-9adc-4252b2c73e15" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_a66cb735-fe29-4120-a522-7012efc71841" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f13ef610-ec5b-43f7-b759-80c0ee145f9a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_a66cb735-fe29-4120-a522-7012efc71841" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f13ef610-ec5b-43f7-b759-80c0ee145f9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_f13ef610-ec5b-43f7-b759-80c0ee145f9a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f13ef610-ec5b-43f7-b759-80c0ee145f9a" xlink:to="loc_us-gaap_ReceivableTypeDomain_f13ef610-ec5b-43f7-b759-80c0ee145f9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_0db0bb37-854d-4e88-b1b1-fd35fbda107f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f13ef610-ec5b-43f7-b759-80c0ee145f9a" xlink:to="loc_us-gaap_ReceivableTypeDomain_0db0bb37-854d-4e88-b1b1-fd35fbda107f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_23be4158-8f16-4fec-aadb-5df4d835884a" xlink:href="sui-20210331.xsd#sui_InstallmentNotesReceivableOnManufacturedHomesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_0db0bb37-854d-4e88-b1b1-fd35fbda107f" xlink:to="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_23be4158-8f16-4fec-aadb-5df4d835884a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NotesduefromRealEstateDevelopersMember_73f4af48-212c-4bfd-8130-d46aec1844ac" xlink:href="sui-20210331.xsd#sui_NotesduefromRealEstateDevelopersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_0db0bb37-854d-4e88-b1b1-fd35fbda107f" xlink:to="loc_sui_NotesduefromRealEstateDevelopersMember_73f4af48-212c-4bfd-8130-d46aec1844ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherReceivablesNetMember_e657636f-aceb-42c2-bfac-f4c60abfea75" xlink:href="sui-20210331.xsd#sui_OtherReceivablesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_0db0bb37-854d-4e88-b1b1-fd35fbda107f" xlink:to="loc_sui_OtherReceivablesNetMember_e657636f-aceb-42c2-bfac-f4c60abfea75" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/NotesAndOtherReceivablesNarrativeDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#NotesAndOtherReceivablesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/NotesAndOtherReceivablesNarrativeDetails" xlink:type="extended" id="i3cf65fea9d8f4882825a7579b9eb54f3_NotesAndOtherReceivablesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestNetAmount_182e1c2f-84fc-42d2-85d8-e7c275b36d45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableWithImputedInterestNetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_ReceivableWithImputedInterestNetAmount_182e1c2f-84fc-42d2-85d8-e7c275b36d45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NotesReceivableFairValueAdjustment_e338b037-a86d-4bb5-b893-4560417d06df" xlink:href="sui-20210331.xsd#sui_NotesReceivableFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_NotesReceivableFairValueAdjustment_e338b037-a86d-4bb5-b893-4560417d06df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsAndNotesReceivableNet_11f1a4f8-b698-41f6-9737-35410ced79de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsAndNotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_AccountsAndNotesReceivableNet_11f1a4f8-b698-41f6-9737-35410ced79de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowance_2dc705b6-553f-4162-aaa9-5f75c52857e0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_LoansAndLeasesReceivableAllowance_2dc705b6-553f-4162-aaa9-5f75c52857e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate_3d21dc71-ac68-4ec8-8354-c1e2fc1dd515" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate_3d21dc71-ac68-4ec8-8354-c1e2fc1dd515" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ReceivableWithImputedInterestTerm_1857b56a-4b6a-40db-b3ca-5ba62342a57a" xlink:href="sui-20210331.xsd#sui_ReceivableWithImputedInterestTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_ReceivableWithImputedInterestTerm_1857b56a-4b6a-40db-b3ca-5ba62342a57a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_UndrawnFundsOnLoans_9fb2fbdc-718f-473f-9d3a-6985a7ed12da" xlink:href="sui-20210331.xsd#sui_UndrawnFundsOnLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_UndrawnFundsOnLoans_9fb2fbdc-718f-473f-9d3a-6985a7ed12da" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_ec1d8ec4-bf5e-4aa6-ac31-525faf6cbd76" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_ec1d8ec4-bf5e-4aa6-ac31-525faf6cbd76" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherReceivablesForRentWaterSewerUsage_92a8260d-86b8-40d9-8c5f-10c222730115" xlink:href="sui-20210331.xsd#sui_OtherReceivablesForRentWaterSewerUsage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_OtherReceivablesForRentWaterSewerUsage_92a8260d-86b8-40d9-8c5f-10c222730115" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AllowanceForRentWaterSewerUsageReceivables_a47525bf-ed07-4156-a537-1b1322be2f8b" xlink:href="sui-20210331.xsd#sui_AllowanceForRentWaterSewerUsageReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_AllowanceForRentWaterSewerUsageReceivables_a47525bf-ed07-4156-a537-1b1322be2f8b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetReclassifiedToReceivable_2cf88a1a-167c-4349-a043-450733628773" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerAssetReclassifiedToReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_ContractWithCustomerAssetReclassifiedToReceivable_2cf88a1a-167c-4349-a043-450733628773" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InsuranceReceivables_66d16b72-2090-4693-926d-7e0725e5189e" xlink:href="sui-20210331.xsd#sui_InsuranceReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_InsuranceReceivables_66d16b72-2090-4693-926d-7e0725e5189e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivables_10521f21-bc68-4664-8730-b0df4dab5c2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_OtherReceivables_10521f21-bc68-4664-8730-b0df4dab5c2d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherReceivablesStorageAndLeasePaymentsMarina_5cf04093-89a3-4f3b-9e8b-64b921a09ba2" xlink:href="sui-20210331.xsd#sui_OtherReceivablesStorageAndLeasePaymentsMarina"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_OtherReceivablesStorageAndLeasePaymentsMarina_5cf04093-89a3-4f3b-9e8b-64b921a09ba2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HomeSaleProceeds_3e9105c8-ff43-430f-b9c9-1d13eb785a4d" xlink:href="sui-20210331.xsd#sui_HomeSaleProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_sui_HomeSaleProceeds_3e9105c8-ff43-430f-b9c9-1d13eb785a4d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_f1d0e75d-0742-426c-9b93-151fd7337128" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_f1d0e75d-0742-426c-9b93-151fd7337128" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5e3486a9-aea0-4446-b687-68fb51655569" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5e3486a9-aea0-4446-b687-68fb51655569" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_37f9db19-bfbc-41de-89ea-bd6874295579" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_37f9db19-bfbc-41de-89ea-bd6874295579" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleNotesPayable_3a0c8539-70de-46b3-8add-230361325e49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleNotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_ConvertibleNotesPayable_3a0c8539-70de-46b3-8add-230361325e49" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLosses_41bb4bf6-1d0a-47b5-abee-23f9cbc84419" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLosses_41bb4bf6-1d0a-47b5-abee-23f9cbc84419" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_99066e8b-7b33-4f47-adf7-a5a9367cde4c" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_cd6e9687-6531-437b-9b62-969ddf3fd9a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_cd6e9687-6531-437b-9b62-969ddf3fd9a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_cd6e9687-6531-437b-9b62-969ddf3fd9a2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_cd6e9687-6531-437b-9b62-969ddf3fd9a2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_cd6e9687-6531-437b-9b62-969ddf3fd9a2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_ad2e4531-25f3-4058-b3cc-27ff9dc9c022" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_cd6e9687-6531-437b-9b62-969ddf3fd9a2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_ad2e4531-25f3-4058-b3cc-27ff9dc9c022" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_f054519d-d4b4-4970-bbf5-a7a4bc6bcf19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_ad2e4531-25f3-4058-b3cc-27ff9dc9c022" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_f054519d-d4b4-4970-bbf5-a7a4bc6bcf19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_b82ba7c7-76c2-4ea0-ac1e-572df904ea08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_b82ba7c7-76c2-4ea0-ac1e-572df904ea08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_b82ba7c7-76c2-4ea0-ac1e-572df904ea08_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_b82ba7c7-76c2-4ea0-ac1e-572df904ea08" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_b82ba7c7-76c2-4ea0-ac1e-572df904ea08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_125483d3-c9b8-4e3f-b9ef-95a549a7b0e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_b82ba7c7-76c2-4ea0-ac1e-572df904ea08" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_125483d3-c9b8-4e3f-b9ef-95a549a7b0e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d91ac8b2-ee43-4888-8b3b-823c8779632a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_125483d3-c9b8-4e3f-b9ef-95a549a7b0e5" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d91ac8b2-ee43-4888-8b3b-823c8779632a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_952257df-2dff-4b80-805b-92292759462f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_125483d3-c9b8-4e3f-b9ef-95a549a7b0e5" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_952257df-2dff-4b80-805b-92292759462f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_3a338c0a-de56-48c1-9b11-c215b6e1f3f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_125483d3-c9b8-4e3f-b9ef-95a549a7b0e5" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_3a338c0a-de56-48c1-9b11-c215b6e1f3f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c5d644b8-812c-467e-95ce-fa554005f8a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c5d644b8-812c-467e-95ce-fa554005f8a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_c5d644b8-812c-467e-95ce-fa554005f8a5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c5d644b8-812c-467e-95ce-fa554005f8a5" xlink:to="loc_us-gaap_ReceivableTypeDomain_c5d644b8-812c-467e-95ce-fa554005f8a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_276b2038-7bd1-4bc2-875b-f850e41fee30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c5d644b8-812c-467e-95ce-fa554005f8a5" xlink:to="loc_us-gaap_ReceivableTypeDomain_276b2038-7bd1-4bc2-875b-f850e41fee30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_f4aa48cd-cf25-452c-a6fb-5cf17302f200" xlink:href="sui-20210331.xsd#sui_InstallmentNotesReceivableOnManufacturedHomesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_276b2038-7bd1-4bc2-875b-f850e41fee30" xlink:to="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_f4aa48cd-cf25-452c-a6fb-5cf17302f200" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NotesduefromRealEstateDevelopersMember_aa85e12f-e594-44af-bc33-e3523f94ba5c" xlink:href="sui-20210331.xsd#sui_NotesduefromRealEstateDevelopersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_276b2038-7bd1-4bc2-875b-f850e41fee30" xlink:to="loc_sui_NotesduefromRealEstateDevelopersMember_aa85e12f-e594-44af-bc33-e3523f94ba5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherReceivablesNetMember_01dccd5b-52f2-4b85-a452-22525dba3d77" xlink:href="sui-20210331.xsd#sui_OtherReceivablesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_276b2038-7bd1-4bc2-875b-f850e41fee30" xlink:to="loc_sui_OtherReceivablesNetMember_01dccd5b-52f2-4b85-a452-22525dba3d77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionAxis_0c40bd20-9610-4b6d-b437-4cd9b64bae88" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_sui_AssetAcquisitionAxis_0c40bd20-9610-4b6d-b437-4cd9b64bae88" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_0c40bd20-9610-4b6d-b437-4cd9b64bae88_default" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_AssetAcquisitionAxis_0c40bd20-9610-4b6d-b437-4cd9b64bae88" xlink:to="loc_sui_AssetAcquisitionDomain_0c40bd20-9610-4b6d-b437-4cd9b64bae88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetAcquisitionDomain_2af4052e-eac5-4437-8a38-ea710f0fb119" xlink:href="sui-20210331.xsd#sui_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_AssetAcquisitionAxis_0c40bd20-9610-4b6d-b437-4cd9b64bae88" xlink:to="loc_sui_AssetAcquisitionDomain_2af4052e-eac5-4437-8a38-ea710f0fb119" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarinasMember_7b22e689-e994-4a79-9c30-eec142ed3543" xlink:href="sui-20210331.xsd#sui_MarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_AssetAcquisitionDomain_2af4052e-eac5-4437-8a38-ea710f0fb119" xlink:to="loc_sui_MarinasMember_7b22e689-e994-4a79-9c30-eec142ed3543" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_083f9860-00c3-40dc-ba1f-0e97f30bccdd" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_083f9860-00c3-40dc-ba1f-0e97f30bccdd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_083f9860-00c3-40dc-ba1f-0e97f30bccdd_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_083f9860-00c3-40dc-ba1f-0e97f30bccdd" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_083f9860-00c3-40dc-ba1f-0e97f30bccdd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_47aabff9-49ac-4f9d-956b-e48d08e1c439" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_083f9860-00c3-40dc-ba1f-0e97f30bccdd" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_47aabff9-49ac-4f9d-956b-e48d08e1c439" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RezPlotMember_59f6d832-4b93-4a03-8b1c-737b74863cae" xlink:href="sui-20210331.xsd#sui_RezPlotMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_47aabff9-49ac-4f9d-956b-e48d08e1c439" xlink:to="loc_sui_RezPlotMember_59f6d832-4b93-4a03-8b1c-737b74863cae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7f785db9-2b07-48eb-aa8b-ec7bea97f843" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_us-gaap_DebtInstrumentAxis_7f785db9-2b07-48eb-aa8b-ec7bea97f843" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7f785db9-2b07-48eb-aa8b-ec7bea97f843_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7f785db9-2b07-48eb-aa8b-ec7bea97f843" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7f785db9-2b07-48eb-aa8b-ec7bea97f843_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_500cdcc4-cd36-4fbc-826b-af730874598e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7f785db9-2b07-48eb-aa8b-ec7bea97f843" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_500cdcc4-cd36-4fbc-826b-af730874598e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertibleSecuredPromissoryNoteMember_079f003a-a8c1-4919-a3b7-e204e756bcac" xlink:href="sui-20210331.xsd#sui_ConvertibleSecuredPromissoryNoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_500cdcc4-cd36-4fbc-826b-af730874598e" xlink:to="loc_sui_ConvertibleSecuredPromissoryNoteMember_079f003a-a8c1-4919-a3b7-e204e756bcac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_22791b42-0f78-4b5f-a91a-bed3977ace26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7613b4d0-7813-4868-b7c5-d77a5aace9f0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_22791b42-0f78-4b5f-a91a-bed3977ace26" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_22791b42-0f78-4b5f-a91a-bed3977ace26_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_22791b42-0f78-4b5f-a91a-bed3977ace26" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_22791b42-0f78-4b5f-a91a-bed3977ace26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_e9da7709-1c0d-4c16-ac82-3c6590d3f797" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_22791b42-0f78-4b5f-a91a-bed3977ace26" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_e9da7709-1c0d-4c16-ac82-3c6590d3f797" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_12d1abfe-a1bd-4048-b2fe-023058139991" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e9da7709-1c0d-4c16-ac82-3c6590d3f797" xlink:to="loc_us-gaap_ConvertibleDebtMember_12d1abfe-a1bd-4048-b2fe-023058139991" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/NotesandOtherReceivablesScheduleofinstallmentnotesreceivableDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#NotesandOtherReceivablesScheduleofinstallmentnotesreceivableDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/NotesandOtherReceivablesScheduleofinstallmentnotesreceivableDetails" xlink:type="extended" id="i9f1a776a832f4fccaf7976efeafb63fc_NotesandOtherReceivablesScheduleofinstallmentnotesreceivableDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableGross_9010d314-04ac-4aa2-9f61-ae869b784b1b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesReceivableGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_us-gaap_NotesReceivableGross_9010d314-04ac-4aa2-9f61-ae869b784b1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancedSalesOfManufacturedHomes_e639763d-5ecd-405f-afbe-14e79ceac054" xlink:href="sui-20210331.xsd#sui_FinancedSalesOfManufacturedHomes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_sui_FinancedSalesOfManufacturedHomes_e639763d-5ecd-405f-afbe-14e79ceac054" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableRelatedPartiesProceeds_a2325120-cde3-4fb2-8db6-70b1460bbbcc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LoansAndLeasesReceivableRelatedPartiesProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_us-gaap_LoansAndLeasesReceivableRelatedPartiesProceeds_a2325120-cde3-4fb2-8db6-70b1460bbbcc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PrincipalReductionFromRepossessedHomes_2c67c3cb-3786-43b5-838d-4e83b495639f" xlink:href="sui-20210331.xsd#sui_PrincipalReductionFromRepossessedHomes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_sui_PrincipalReductionFromRepossessedHomes_2c67c3cb-3786-43b5-838d-4e83b495639f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableGross_883bdb52-66a2-4d2a-90a9-38d834bda557" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesReceivableGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NotesReceivableFairValueAdjustment_2f8572b9-4d9f-4b66-a433-9fec7c27f840" xlink:href="sui-20210331.xsd#sui_NotesReceivableFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_sui_NotesReceivableFairValueAdjustment_2f8572b9-4d9f-4b66-a433-9fec7c27f840" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet_193fec27-65e4-4ada-890d-59f97b21ed1f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet_193fec27-65e4-4ada-890d-59f97b21ed1f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestNetAmount_021e1405-cc42-4a94-b8d2-d2d1e2a19ceb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableWithImputedInterestNetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_us-gaap_ReceivableWithImputedInterestNetAmount_021e1405-cc42-4a94-b8d2-d2d1e2a19ceb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AssetsHeldForSaleAdjustmentOfNotesReceivable_b9221abf-7117-43c3-9e38-c67c1583c735" xlink:href="sui-20210331.xsd#sui_AssetsHeldForSaleAdjustmentOfNotesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_sui_AssetsHeldForSaleAdjustmentOfNotesReceivable_b9221abf-7117-43c3-9e38-c67c1583c735" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ScheduleOfInstallmentNotesReceivableTable_2b631e94-2012-423d-831b-96dcc1d81ca0" xlink:href="sui-20210331.xsd#sui_ScheduleOfInstallmentNotesReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_3d3d1643-99a9-4bda-a1e9-b421b43949ac" xlink:to="loc_sui_ScheduleOfInstallmentNotesReceivableTable_2b631e94-2012-423d-831b-96dcc1d81ca0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f218188f-5256-4689-8af6-8e29f92fa7d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_sui_ScheduleOfInstallmentNotesReceivableTable_2b631e94-2012-423d-831b-96dcc1d81ca0" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f218188f-5256-4689-8af6-8e29f92fa7d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_f218188f-5256-4689-8af6-8e29f92fa7d1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f218188f-5256-4689-8af6-8e29f92fa7d1" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_f218188f-5256-4689-8af6-8e29f92fa7d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_46b8e9ad-c62c-4114-97a2-fd46243640af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_f218188f-5256-4689-8af6-8e29f92fa7d1" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_46b8e9ad-c62c-4114-97a2-fd46243640af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_030fba5e-f02b-432e-9f01-2079c884c526" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_46b8e9ad-c62c-4114-97a2-fd46243640af" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_030fba5e-f02b-432e-9f01-2079c884c526" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_e48007aa-fdc3-4487-8d01-160abbd186a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_sui_ScheduleOfInstallmentNotesReceivableTable_2b631e94-2012-423d-831b-96dcc1d81ca0" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_e48007aa-fdc3-4487-8d01-160abbd186a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_e48007aa-fdc3-4487-8d01-160abbd186a6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_e48007aa-fdc3-4487-8d01-160abbd186a6" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_e48007aa-fdc3-4487-8d01-160abbd186a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e3e258b1-6d94-4d48-bf85-c4d5da6a951f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_e48007aa-fdc3-4487-8d01-160abbd186a6" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e3e258b1-6d94-4d48-bf85-c4d5da6a951f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c7b49b5c-cc01-4ee2-a781-3f8e4b137d3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e3e258b1-6d94-4d48-bf85-c4d5da6a951f" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c7b49b5c-cc01-4ee2-a781-3f8e4b137d3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_58ea0510-e70c-40f7-bc23-d27ecb8d15b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e3e258b1-6d94-4d48-bf85-c4d5da6a951f" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_58ea0510-e70c-40f7-bc23-d27ecb8d15b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_04e61624-3f17-46f0-a353-e56b250895ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e3e258b1-6d94-4d48-bf85-c4d5da6a951f" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_04e61624-3f17-46f0-a353-e56b250895ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_9f1eb162-39bf-4cff-9c72-d35ad2661c26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_sui_ScheduleOfInstallmentNotesReceivableTable_2b631e94-2012-423d-831b-96dcc1d81ca0" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_9f1eb162-39bf-4cff-9c72-d35ad2661c26" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_9f1eb162-39bf-4cff-9c72-d35ad2661c26_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_9f1eb162-39bf-4cff-9c72-d35ad2661c26" xlink:to="loc_us-gaap_ReceivableTypeDomain_9f1eb162-39bf-4cff-9c72-d35ad2661c26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_6c30b70e-5766-4035-97a3-5c3f54516c8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_9f1eb162-39bf-4cff-9c72-d35ad2661c26" xlink:to="loc_us-gaap_ReceivableTypeDomain_6c30b70e-5766-4035-97a3-5c3f54516c8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InstallmentNotesReceivableOnManufacturedHomesGrossMember_e249561d-f92b-40ec-a46c-3b948d49b4a7" xlink:href="sui-20210331.xsd#sui_InstallmentNotesReceivableOnManufacturedHomesGrossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_6c30b70e-5766-4035-97a3-5c3f54516c8a" xlink:to="loc_sui_InstallmentNotesReceivableOnManufacturedHomesGrossMember_e249561d-f92b-40ec-a46c-3b948d49b4a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CollateralizedReceivablesNetAndInstallmentNotesReceivablesOnManufacturedHomesMember_b59534b1-4ae4-4896-869a-22549f820252" xlink:href="sui-20210331.xsd#sui_CollateralizedReceivablesNetAndInstallmentNotesReceivablesOnManufacturedHomesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_6c30b70e-5766-4035-97a3-5c3f54516c8a" xlink:to="loc_sui_CollateralizedReceivablesNetAndInstallmentNotesReceivablesOnManufacturedHomesMember_b59534b1-4ae4-4896-869a-22549f820252" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_e33a754a-05bd-4990-80c6-0bd398c4837f" xlink:href="sui-20210331.xsd#sui_InstallmentNotesReceivableOnManufacturedHomesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_6c30b70e-5766-4035-97a3-5c3f54516c8a" xlink:to="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_e33a754a-05bd-4990-80c6-0bd398c4837f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IntangibleAssets" xlink:type="simple" xlink:href="sui-20210331.xsd#IntangibleAssets"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IntangibleAssets" xlink:type="extended" id="i1b5e6f9fa0244f25a661ccd6e4a0eb49_IntangibleAssets"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsTables" xlink:type="simple" xlink:href="sui-20210331.xsd#IntangibleAssetsIntangibleAssetsTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsTables" xlink:type="extended" id="i738655cde96a41beb426fb7638a95c5f_IntangibleAssetsIntangibleAssetsTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#IntangibleAssetsIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="extended" id="ib721bea7f34e46f2a282f0d8952792b5_IntangibleAssetsIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_d64429a9-7151-404a-98b1-7828b04c0da5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_d64429a9-7151-404a-98b1-7828b04c0da5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_4da6d6c0-2a21-4db8-81fd-59db8a9792f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_4da6d6c0-2a21-4db8-81fd-59db8a9792f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_cf52c577-57ee-45ae-a5d9-b5eba41b4be8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_cf52c577-57ee-45ae-a5d9-b5eba41b4be8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_ec06ffa9-f0cd-460d-8100-4ca2f0423625" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_Goodwill_ec06ffa9-f0cd-460d-8100-4ca2f0423625" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_53072e82-7318-4032-8e0f-947dce0c6795" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_53072e82-7318-4032-8e0f-947dce0c6795" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9e262d6d-91d5-416b-a1c9-c0b0b1e0d2f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_17407963-b1a4-4e47-b707-9eff92796449" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9e262d6d-91d5-416b-a1c9-c0b0b1e0d2f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6de6d42d-dc21-41ab-bbaf-fda1dec3675e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9e262d6d-91d5-416b-a1c9-c0b0b1e0d2f8" xlink:to="loc_srt_RangeAxis_6de6d42d-dc21-41ab-bbaf-fda1dec3675e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6de6d42d-dc21-41ab-bbaf-fda1dec3675e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6de6d42d-dc21-41ab-bbaf-fda1dec3675e" xlink:to="loc_srt_RangeMember_6de6d42d-dc21-41ab-bbaf-fda1dec3675e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_47e06b56-c777-46aa-ad34-449491b174eb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6de6d42d-dc21-41ab-bbaf-fda1dec3675e" xlink:to="loc_srt_RangeMember_47e06b56-c777-46aa-ad34-449491b174eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cc04bc31-5674-480b-ae6c-aafed77c8660" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_47e06b56-c777-46aa-ad34-449491b174eb" xlink:to="loc_srt_MinimumMember_cc04bc31-5674-480b-ae6c-aafed77c8660" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_061ad1a7-9cf2-415b-adc1-b920ddb203ed" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_47e06b56-c777-46aa-ad34-449491b174eb" xlink:to="loc_srt_MaximumMember_061ad1a7-9cf2-415b-adc1-b920ddb203ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_7e23ed12-4721-4063-a04f-1594f9db1513" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9e262d6d-91d5-416b-a1c9-c0b0b1e0d2f8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_7e23ed12-4721-4063-a04f-1594f9db1513" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7e23ed12-4721-4063-a04f-1594f9db1513_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_7e23ed12-4721-4063-a04f-1594f9db1513" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7e23ed12-4721-4063-a04f-1594f9db1513_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_7e23ed12-4721-4063-a04f-1594f9db1513" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAcquiredInPlaceMember_156c71a3-cf21-467d-b70c-bec6becb0b06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAcquiredInPlaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:to="loc_us-gaap_LeasesAcquiredInPlaceMember_156c71a3-cf21-467d-b70c-bec6becb0b06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FranchiseRightsMember_91d02749-40ff-44e5-9bd9-519510702193" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FranchiseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:to="loc_us-gaap_FranchiseRightsMember_91d02749-40ff-44e5-9bd9-519510702193" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_24a1bfdb-69d6-4e89-9352-23d3594e82b3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_24a1bfdb-69d6-4e89-9352-23d3594e82b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_a7f300d6-95e9-437a-acba-c1a03b2b8ada" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:to="loc_us-gaap_CustomerRelationshipsMember_a7f300d6-95e9-437a-acba-c1a03b2b8ada" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_e9d98922-1f96-49be-94df-64623ed71fd2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_67b02829-7dd6-4dfc-8306-2e3030b895f8" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_e9d98922-1f96-49be-94df-64623ed71fd2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsScheduleofIntangibleAssetAmortizationExpenseDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#IntangibleAssetsIntangibleAssetsScheduleofIntangibleAssetAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IntangibleAssetsIntangibleAssetsScheduleofIntangibleAssetAmortizationExpenseDetails" xlink:type="extended" id="i9d6cc7d349704318959ff2f52da1278a_IntangibleAssetsIntangibleAssetsScheduleofIntangibleAssetAmortizationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b8b53d17-144e-46e7-b557-a10c99af9275" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_0d290479-6ce0-455d-8843-415bc955404d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b8b53d17-144e-46e7-b557-a10c99af9275" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_0d290479-6ce0-455d-8843-415bc955404d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_fed2feb7-f142-4cae-be65-7819474dabe5" xlink:href="sui-20210331.xsd#sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b8b53d17-144e-46e7-b557-a10c99af9275" xlink:to="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_fed2feb7-f142-4cae-be65-7819474dabe5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2fe9fb8b-bfeb-4954-98a6-98ad73110a23" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_fed2feb7-f142-4cae-be65-7819474dabe5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2fe9fb8b-bfeb-4954-98a6-98ad73110a23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2fe9fb8b-bfeb-4954-98a6-98ad73110a23_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2fe9fb8b-bfeb-4954-98a6-98ad73110a23" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2fe9fb8b-bfeb-4954-98a6-98ad73110a23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2fe9fb8b-bfeb-4954-98a6-98ad73110a23" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAcquiredInPlaceMember_7ddad47f-e1d2-4121-8bd4-31eface263c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAcquiredInPlaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:to="loc_us-gaap_LeasesAcquiredInPlaceMember_7ddad47f-e1d2-4121-8bd4-31eface263c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FranchiseRightsMember_e11a334d-372b-406a-b6d6-c6369ff93538" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FranchiseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:to="loc_us-gaap_FranchiseRightsMember_e11a334d-372b-406a-b6d6-c6369ff93538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_c8729ccd-b78f-4d2e-b0c3-c584dc96323c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_c8729ccd-b78f-4d2e-b0c3-c584dc96323c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_01499787-4f05-4a51-a4d3-9ef454c1b8b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_01499787-4f05-4a51-a4d3-9ef454c1b8b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_15208315-b5d6-42f6-87a8-3b50472f29d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4f69c669-b9f7-40e3-bdc3-69652bceb42f" xlink:to="loc_us-gaap_CustomerRelationshipsMember_15208315-b5d6-42f6-87a8-3b50472f29d4" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IntangibleAssetsIntangiblesFutureAmortizationExpenseDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#IntangibleAssetsIntangiblesFutureAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IntangibleAssetsIntangiblesFutureAmortizationExpenseDetails" xlink:type="extended" id="i7b58877c3e0e42d8997800b205df7c7d_IntangibleAssetsIntangiblesFutureAmortizationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7dbf8f17-5167-4178-abbf-2b68f266b1dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7dbf8f17-5167-4178-abbf-2b68f266b1dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b658906b-40db-4c64-9c91-4e35a927c07b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b658906b-40db-4c64-9c91-4e35a927c07b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_977de31a-3499-4126-bc16-72ff7e689059" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_977de31a-3499-4126-bc16-72ff7e689059" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_2e5a374c-9e0b-4a18-9261-315a3e311ca5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_2e5a374c-9e0b-4a18-9261-315a3e311ca5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_f21b5b7d-6bfe-4c70-8e2a-474a08cba32e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_f21b5b7d-6bfe-4c70-8e2a-474a08cba32e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_bfae8ed9-9058-4237-afe6-b24f20901780" xlink:href="sui-20210331.xsd#sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e36639ba-020d-4138-9f48-6158cb1f7738" xlink:to="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_bfae8ed9-9058-4237-afe6-b24f20901780" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e324f861-f585-43d1-8715-c9bc3b190a8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_sui_ScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseTable_bfae8ed9-9058-4237-afe6-b24f20901780" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e324f861-f585-43d1-8715-c9bc3b190a8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e324f861-f585-43d1-8715-c9bc3b190a8a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e324f861-f585-43d1-8715-c9bc3b190a8a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e324f861-f585-43d1-8715-c9bc3b190a8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e324f861-f585-43d1-8715-c9bc3b190a8a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_00098479-38bb-4a4a-bca2-0d3978e2a9f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_CustomerRelationshipsMember_00098479-38bb-4a4a-bca2-0d3978e2a9f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FranchiseRightsMember_2114dd4d-ad73-4ef1-bcfd-3fd225389a7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FranchiseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_FranchiseRightsMember_2114dd4d-ad73-4ef1-bcfd-3fd225389a7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAcquiredInPlaceMember_e1968e3c-aade-4593-8fa5-ec15d4e9ce05" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAcquiredInPlaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_LeasesAcquiredInPlaceMember_e1968e3c-aade-4593-8fa5-ec15d4e9ce05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAcquiredInPlaceMarketAdjustmentMember_d2021b5d-c2d6-4c6b-ae16-dc7e772c9268" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAcquiredInPlaceMarketAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_LeasesAcquiredInPlaceMarketAdjustmentMember_d2021b5d-c2d6-4c6b-ae16-dc7e772c9268" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_b61b3d35-f54a-4a3b-a50f-95f6a4652128" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_b61b3d35-f54a-4a3b-a50f-95f6a4652128" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_4e94cb4e-97b9-49f3-a500-053d21eed29e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d6665833-6a6f-4f4a-aa3a-d5fb25de2635" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_4e94cb4e-97b9-49f3-a500-053d21eed29e" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/InvestmentInAffiliates" xlink:type="simple" xlink:href="sui-20210331.xsd#InvestmentInAffiliates"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/InvestmentInAffiliates" xlink:type="extended" id="i25d17952e7c44a0a9919627d83f7db24_InvestmentInAffiliates"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/InvestmentInAffiliatesTables" xlink:type="simple" xlink:href="sui-20210331.xsd#InvestmentInAffiliatesTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/InvestmentInAffiliatesTables" xlink:type="extended" id="ic720e0b837324f56af70be70d830d69c_InvestmentInAffiliatesTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/InvestmentInAffiliatesNarrativeDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#InvestmentInAffiliatesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/InvestmentInAffiliatesNarrativeDetails" xlink:type="extended" id="ie3be24148cf041fb97cbf08db8d225d3_InvestmentInAffiliatesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_97386316-670f-4885-ab9c-851ae8624f5d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_21f39bf4-1404-4d44-967a-8a6dcecdeb41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_97386316-670f-4885-ab9c-851ae8624f5d" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_21f39bf4-1404-4d44-967a-8a6dcecdeb41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0f746bcb-826b-4b23-869f-1eff3b551736" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_97386316-670f-4885-ab9c-851ae8624f5d" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0f746bcb-826b-4b23-869f-1eff3b551736" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_e9013cf1-f685-4bc5-b674-09afadb3993f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0f746bcb-826b-4b23-869f-1eff3b551736" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_e9013cf1-f685-4bc5-b674-09afadb3993f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_e9013cf1-f685-4bc5-b674-09afadb3993f_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_e9013cf1-f685-4bc5-b674-09afadb3993f" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_e9013cf1-f685-4bc5-b674-09afadb3993f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_e9013cf1-f685-4bc5-b674-09afadb3993f" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RezPlotMember_aa1545fc-c832-4ac8-a9cd-ea20bd70b904" xlink:href="sui-20210331.xsd#sui_RezPlotMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:to="loc_sui_RezPlotMember_aa1545fc-c832-4ac8-a9cd-ea20bd70b904" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SungeniaJVMember_6abf5821-384b-4895-a225-fa671f36f8e1" xlink:href="sui-20210331.xsd#sui_SungeniaJVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:to="loc_sui_SungeniaJVMember_6abf5821-384b-4895-a225-fa671f36f8e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GTSCMember_03604047-4c64-43df-a7f6-5faa8982712b" xlink:href="sui-20210331.xsd#sui_GTSCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:to="loc_sui_GTSCMember_03604047-4c64-43df-a7f6-5faa8982712b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OrigenFinancialServicesMember_5cfc13b0-4f4b-4dd6-87ee-2970d3b80f3c" xlink:href="sui-20210331.xsd#sui_OrigenFinancialServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:to="loc_sui_OrigenFinancialServicesMember_5cfc13b0-4f4b-4dd6-87ee-2970d3b80f3c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SVLiftMember_df42c154-d36f-4a49-96d1-32e00a9a41db" xlink:href="sui-20210331.xsd#sui_SVLiftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_93641591-a3c4-4198-80b4-b04e8d4f0901" xlink:to="loc_sui_SVLiftMember_df42c154-d36f-4a49-96d1-32e00a9a41db" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/InvestmentinAffiliatesInvestmentBalanceDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#InvestmentinAffiliatesInvestmentBalanceDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/InvestmentinAffiliatesInvestmentBalanceDetails" xlink:type="extended" id="ie974a06050c2444cba83bd0aa5a9f50f_InvestmentinAffiliatesInvestmentBalanceDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_36135d78-1cb3-45c5-b387-be1c0e7b807e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_36135d78-1cb3-45c5-b387-be1c0e7b807e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityMethodInvestmentFairValueAdjustment_cd4bd0d8-dd6a-447e-b496-bfde6ff38e19" xlink:href="sui-20210331.xsd#sui_EquityMethodInvestmentFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_sui_EquityMethodInvestmentFairValueAdjustment_cd4bd0d8-dd6a-447e-b496-bfde6ff38e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_150eb2e2-e7c4-4463-a413-72ef9c68fcab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_us-gaap_EquityMethodInvestments_150eb2e2-e7c4-4463-a413-72ef9c68fcab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityMethodInvestmentAdjustmentAllowanceforLosses_480b1ed0-b142-4344-82c5-83bf64d6425d" xlink:href="sui-20210331.xsd#sui_EquityMethodInvestmentAdjustmentAllowanceforLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_sui_EquityMethodInvestmentAdjustmentAllowanceforLosses_480b1ed0-b142-4344-82c5-83bf64d6425d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityMethodInvestmentsInitialFairValueAdjustment_1161dcfe-a89d-484e-9d16-323798bafb5d" xlink:href="sui-20210331.xsd#sui_EquityMethodInvestmentsInitialFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_sui_EquityMethodInvestmentsInitialFairValueAdjustment_1161dcfe-a89d-484e-9d16-323798bafb5d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityMethodInvestmentCashContributions_1260f701-dc9e-4bf4-bab3-784af69ffba9" xlink:href="sui-20210331.xsd#sui_EquityMethodInvestmentCashContributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_sui_EquityMethodInvestmentCashContributions_1260f701-dc9e-4bf4-bab3-784af69ffba9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_17020f5c-5f0a-47c6-8e69-d9a750d14757" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_17020f5c-5f0a-47c6-8e69-d9a750d14757" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityMethodInvestmentCumulativeTranslationAdjustment_b051fcc7-b078-44f1-a185-683276e8dbd5" xlink:href="sui-20210331.xsd#sui_EquityMethodInvestmentCumulativeTranslationAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_sui_EquityMethodInvestmentCumulativeTranslationAdjustment_b051fcc7-b078-44f1-a185-683276e8dbd5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireEquityMethodInvestments_369d81d3-9d82-4593-a27e-8e1faacb8e15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_us-gaap_PaymentsToAcquireEquityMethodInvestments_369d81d3-9d82-4593-a27e-8e1faacb8e15" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_bd103446-f144-41c4-b77c-8bd4c687ec98" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_3dd6fc29-eda9-46d9-9a2d-96cc082bfdde" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_bd103446-f144-41c4-b77c-8bd4c687ec98" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6db6adb8-e577-4925-8b84-dce1473ec523" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_bd103446-f144-41c4-b77c-8bd4c687ec98" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6db6adb8-e577-4925-8b84-dce1473ec523" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_6db6adb8-e577-4925-8b84-dce1473ec523_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6db6adb8-e577-4925-8b84-dce1473ec523" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_6db6adb8-e577-4925-8b84-dce1473ec523_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6db6adb8-e577-4925-8b84-dce1473ec523" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RezPlotMember_d2e7a4d2-a5df-4c64-8bb3-8d90d6c911f9" xlink:href="sui-20210331.xsd#sui_RezPlotMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:to="loc_sui_RezPlotMember_d2e7a4d2-a5df-4c64-8bb3-8d90d6c911f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SungeniaJVMember_17c0d108-8128-43d8-92dc-c21abdfaf7e4" xlink:href="sui-20210331.xsd#sui_SungeniaJVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:to="loc_sui_SungeniaJVMember_17c0d108-8128-43d8-92dc-c21abdfaf7e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GTSCMember_eb4be39a-2977-41ab-817c-fd68e5238e6d" xlink:href="sui-20210331.xsd#sui_GTSCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:to="loc_sui_GTSCMember_eb4be39a-2977-41ab-817c-fd68e5238e6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OrigenFinancialServicesMember_367d5cc6-3de1-4fce-bacb-304b18edcd91" xlink:href="sui-20210331.xsd#sui_OrigenFinancialServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:to="loc_sui_OrigenFinancialServicesMember_367d5cc6-3de1-4fce-bacb-304b18edcd91" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SVLiftMember_5091e9bb-d525-4ba3-9e6c-c4d5443a1d8b" xlink:href="sui-20210331.xsd#sui_SVLiftMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b9fb1095-b1a8-4752-8356-2261a878e0d0" xlink:to="loc_sui_SVLiftMember_5091e9bb-d525-4ba3-9e6c-c4d5443a1d8b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntities" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedVariableInterestEntities"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntities" xlink:type="extended" id="ice538539d6f445558ebe5bca7446a517_ConsolidatedVariableInterestEntities"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntitiesTables" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedVariableInterestEntitiesTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntitiesTables" xlink:type="extended" id="i83a009e39f364ce5a985cb5c0580d921_ConsolidatedVariableInterestEntitiesTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntitiesScheduleofVariableInterestEntitiesDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#ConsolidatedVariableInterestEntitiesScheduleofVariableInterestEntitiesDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ConsolidatedVariableInterestEntitiesScheduleofVariableInterestEntitiesDetails" xlink:type="extended" id="i1be91313154f43a696d8a63a8177b7ad_ConsolidatedVariableInterestEntitiesScheduleofVariableInterestEntitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyNet_eaeef41b-6227-4731-a457-61b32199ca80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyNet_eaeef41b-6227-4731-a457-61b32199ca80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_4aff40f8-8a90-4813-830f-ba9e78df292a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_OtherAssets_4aff40f8-8a90-4813-830f-ba9e78df292a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_d0c5ab9f-e99f-4fc1-b15f-2bbc16e65904" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_SecuredDebt_d0c5ab9f-e99f-4fc1-b15f-2bbc16e65904" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_f7249f09-d760-48d9-ad18-8996ea513e29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_f7249f09-d760-48d9-ad18-8996ea513e29" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_765f63c5-3b38-431a-ad48-f6e19401cdec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_OtherLiabilities_765f63c5-3b38-431a-ad48-f6e19401cdec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_9d0bc022-fb4e-4a40-97e7-47f8928d860d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_Liabilities_9d0bc022-fb4e-4a40-97e7-47f8928d860d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityInterests_bc6e5f0d-5466-4aae-8b16-7ce983bd2f06" xlink:href="sui-20210331.xsd#sui_EquityInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_sui_EquityInterests_bc6e5f0d-5466-4aae-8b16-7ce983bd2f06" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestInVariableInterestEntity_7e72f2ee-2b1b-4e9f-8910-9c1bd475dcfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestInVariableInterestEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_NoncontrollingInterestInVariableInterestEntity_7e72f2ee-2b1b-4e9f-8910-9c1bd475dcfb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntitiesConsolidatedTotalLiabilitiesAndStockholdersEquity_a452e531-40fb-4c05-a7a0-d25fd5ea68f2" xlink:href="sui-20210331.xsd#sui_VariableInterestEntitiesConsolidatedTotalLiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_sui_VariableInterestEntitiesConsolidatedTotalLiabilitiesAndStockholdersEquity_a452e531-40fb-4c05-a7a0-d25fd5ea68f2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityasaPercentageofConsolidatedAssets_500017e3-09d4-4228-aa4d-e6928bc8be79" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityasaPercentageofConsolidatedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_sui_VariableInterestEntityasaPercentageofConsolidatedAssets_500017e3-09d4-4228-aa4d-e6928bc8be79" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityasaPercentageofConsolidatedLiabilities_b68e0fd6-91b8-47e2-8368-1d90f51d7029" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityasaPercentageofConsolidatedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_sui_VariableInterestEntityasaPercentageofConsolidatedLiabilities_b68e0fd6-91b8-47e2-8368-1d90f51d7029" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VIEasaPercentageofTotalEquity_968486ab-ecc7-4515-aee2-bbf3049606c4" xlink:href="sui-20210331.xsd#sui_VIEasaPercentageofTotalEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_sui_VIEasaPercentageofTotalEquity_968486ab-ecc7-4515-aee2-bbf3049606c4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_a5ee8d56-28c7-43e8-aca0-8d707e452adc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_Assets_a5ee8d56-28c7-43e8-aca0-8d707e452adc" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e445c60d-f713-44b0-9941-ace496e40962" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c8c7bb69-ec2a-4967-ad05-3470c36b72dd" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e445c60d-f713-44b0-9941-ace496e40962" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_4b86f51b-8151-4d94-b081-665b95870d61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_e445c60d-f713-44b0-9941-ace496e40962" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_4b86f51b-8151-4d94-b081-665b95870d61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_4b86f51b-8151-4d94-b081-665b95870d61_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_4b86f51b-8151-4d94-b081-665b95870d61" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_4b86f51b-8151-4d94-b081-665b95870d61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_286f3bda-52f6-4f88-8bd0-e08c6b959012" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_4b86f51b-8151-4d94-b081-665b95870d61" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_286f3bda-52f6-4f88-8bd0-e08c6b959012" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_7553435e-e748-4feb-977f-58c094270e89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_286f3bda-52f6-4f88-8bd0-e08c6b959012" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_7553435e-e748-4feb-977f-58c094270e89" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCredit" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCredit"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCredit" xlink:type="extended" id="i31c88a54a44b4095be7302e124698495_DebtAndLinesOfCredit"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCreditTables" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCreditTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCreditTables" xlink:type="extended" id="i6d64145bba0644e1a07f28dfe659a529_DebtAndLinesOfCreditTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCreditScheduleofdebtandlinesofcreditDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCreditScheduleofdebtandlinesofcreditDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCreditScheduleofdebtandlinesofcreditDetails" xlink:type="extended" id="i5d50c6f5cf0b4df7933b8df2bf6a79e5_DebtAndLinesOfCreditScheduleofdebtandlinesofcreditDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_f316b411-3249-461a-8d33-9368fec603b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_f316b411-3249-461a-8d33-9368fec603b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_a078bcd5-7724-4130-b01c-298774e33767" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_a078bcd5-7724-4130-b01c-298774e33767" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_61d106e0-fc84-4038-bb82-a0867321b034" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_61d106e0-fc84-4038-bb82-a0867321b034" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_95eee4bf-b606-4239-aa43-3fe1d2dba8ec" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_dei_DocumentPeriodEndDate_95eee4bf-b606-4239-aa43-3fe1d2dba8ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_1efa43c8-2136-4528-bcf1-a04a4a8e335d" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_1efa43c8-2136-4528-bcf1-a04a4a8e335d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_b9a3196d-beb2-47be-84bb-aa59b01d54fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_SecuredDebt_b9a3196d-beb2-47be-84bb-aa59b01d54fa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_1e9c3de2-d901-41de-8120-a3bbc8efdf57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_1e9c3de2-d901-41de-8120-a3bbc8efdf57" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_5d6bd7a5-7865-484f-a1d0-1a5c421fe3c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtInstrumentTerm_5d6bd7a5-7865-484f-a1d0-1a5c421fe3c3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d0191c2e-2d2a-4bb1-a2f1-b7a5489be533" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d0191c2e-2d2a-4bb1-a2f1-b7a5489be533" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherBorrowings_7f01e037-9c06-4256-a3eb-f833fa795562" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_OtherBorrowings_7f01e037-9c06-4256-a3eb-f833fa795562" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Debtweightedaveragetomaturitylength_af876ef0-cac4-4951-a4d0-57c6c008dc53" xlink:href="sui-20210331.xsd#sui_Debtweightedaveragetomaturitylength"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_sui_Debtweightedaveragetomaturitylength_af876ef0-cac4-4951-a4d0-57c6c008dc53" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_c6e0d7fd-5fdf-48c1-ae59-883b72bd5473" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_c6e0d7fd-5fdf-48c1-ae59-883b72bd5473" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_3cc70734-37d3-43ac-be6d-229227638bef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_LineOfCredit_3cc70734-37d3-43ac-be6d-229227638bef" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SecuredDebtAndOtherBorrowings_83809057-60bf-40a9-889e-3ed083921874" xlink:href="sui-20210331.xsd#sui_SecuredDebtAndOtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_sui_SecuredDebtAndOtherBorrowings_83809057-60bf-40a9-889e-3ed083921874" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_89effdb0-2dde-4e33-8da7-eb15b197c0c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_89effdb0-2dde-4e33-8da7-eb15b197c0c1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofRealEstateUnitsReleased_1163fa05-3faf-4eb3-95ab-c09ef30a5f82" xlink:href="sui-20210331.xsd#sui_NumberofRealEstateUnitsReleased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_sui_NumberofRealEstateUnitsReleased_1163fa05-3faf-4eb3-95ab-c09ef30a5f82" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_989c01bd-a231-4a61-ade1-c3d9f36e1ae7" xlink:to="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:to="loc_us-gaap_CreditFacilityAxis_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f" xlink:to="loc_us-gaap_CreditFacilityDomain_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_0aef4ffc-72d0-42e8-815d-f34ca20f3a9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_bc8f6fc1-a6d8-42f7-81c2-b7c90877371f" xlink:to="loc_us-gaap_CreditFacilityDomain_0aef4ffc-72d0-42e8-815d-f34ca20f3a9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_e2c3c15e-4257-49fa-8975-873c3538dd5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0aef4ffc-72d0-42e8-815d-f34ca20f3a9f" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_e2c3c15e-4257-49fa-8975-873c3538dd5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_788afac8-7411-4d44-aba1-43cd3e36bb78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_788afac8-7411-4d44-aba1-43cd3e36bb78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_788afac8-7411-4d44-aba1-43cd3e36bb78_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_788afac8-7411-4d44-aba1-43cd3e36bb78" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_788afac8-7411-4d44-aba1-43cd3e36bb78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_77e8afaa-f6a4-4984-b22c-bf8c6252dc9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_788afac8-7411-4d44-aba1-43cd3e36bb78" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_77e8afaa-f6a4-4984-b22c-bf8c6252dc9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_2464c2fd-53c9-45da-ade2-72d4b81f119d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_77e8afaa-f6a4-4984-b22c-bf8c6252dc9f" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_2464c2fd-53c9-45da-ade2-72d4b81f119d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_b1e8439f-f41e-4f35-9441-a85e75f643a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_2464c2fd-53c9-45da-ade2-72d4b81f119d" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_b1e8439f-f41e-4f35-9441-a85e75f643a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:to="loc_us-gaap_DebtInstrumentAxis_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7bc29ede-c6e5-4afd-a5b6-cfebe88ae2ea" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesDecember12021598PercentInterestRateMember_29dcbefb-01fc-4c64-a09a-837e45ee5216" xlink:href="sui-20210331.xsd#sui_MaturesDecember12021598PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesDecember12021598PercentInterestRateMember_29dcbefb-01fc-4c64-a09a-837e45ee5216" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesMarch120215.837PercentInterestRateMemberDomainDomain_c670461c-3343-4909-813a-a9eff13ed844" xlink:href="sui-20210331.xsd#sui_MaturesMarch120215.837PercentInterestRateMemberDomainDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesMarch120215.837PercentInterestRateMemberDomainDomain_c670461c-3343-4909-813a-a9eff13ed844" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesJuly120205.86PercentInterestRateMemberDomain_aab7fa93-433f-4c55-862d-a7a7af646e88" xlink:href="sui-20210331.xsd#sui_MaturesJuly120205.86PercentInterestRateMemberDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesJuly120205.86PercentInterestRateMemberDomain_aab7fa93-433f-4c55-862d-a7a7af646e88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesMarch120205.62PercentInterestRateMember_8f1fb3b4-131f-4805-95c6-0c409fa35d15" xlink:href="sui-20210331.xsd#sui_MaturesMarch120205.62PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesMarch120205.62PercentInterestRateMember_8f1fb3b4-131f-4805-95c6-0c409fa35d15" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_4baba4d3-fd49-4e1c-892c-baa077c8bebb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember_4baba4d3-fd49-4e1c-892c-baa077c8bebb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LifeCompaniesMember_36f5221e-f42b-4760-a4fc-ebd9dd995a74" xlink:href="sui-20210331.xsd#sui_LifeCompaniesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_LifeCompaniesMember_36f5221e-f42b-4760-a4fc-ebd9dd995a74" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_3a71fa21-9220-4d54-9b40-035b6dee31da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember_3a71fa21-9220-4d54-9b40-035b6dee31da" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesNovember120215.10PercentInterestRateMember_3fc07502-8158-4f5a-a31b-60e7824475d7" xlink:href="sui-20210331.xsd#sui_MaturesNovember120215.10PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesNovember120215.10PercentInterestRateMember_3fc07502-8158-4f5a-a31b-60e7824475d7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesMarch1andApril120206.24PercentInterestRateMember_ed87aae8-b1d1-4cc5-9f57-cdb77ad0f208" xlink:href="sui-20210331.xsd#sui_MaturesMarch1andApril120206.24PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesMarch1andApril120206.24PercentInterestRateMember_ed87aae8-b1d1-4cc5-9f57-cdb77ad0f208" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesMay120234.3PercentInterestRateMember_8511fa98-31f9-4531-b27d-5c23a99eb7af" xlink:href="sui-20210331.xsd#sui_MaturesMay120234.3PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesMay120234.3PercentInterestRateMember_8511fa98-31f9-4531-b27d-5c23a99eb7af" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MaturesJanuary120303.83PercentInterestRateMember_53e72fcb-d919-4afa-8eec-b18b16da5869" xlink:href="sui-20210331.xsd#sui_MaturesJanuary120303.83PercentInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79267839-e9f5-4f11-ae08-2ce725b9aedb" xlink:to="loc_sui_MaturesJanuary120303.83PercentInterestRateMember_53e72fcb-d919-4afa-8eec-b18b16da5869" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_798c9c23-09aa-4cde-a327-5aeee81c652e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_05ad9655-4df1-4b1d-8741-bdd4da9aac9f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_798c9c23-09aa-4cde-a327-5aeee81c652e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_798c9c23-09aa-4cde-a327-5aeee81c652e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_798c9c23-09aa-4cde-a327-5aeee81c652e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_798c9c23-09aa-4cde-a327-5aeee81c652e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_798c9c23-09aa-4cde-a327-5aeee81c652e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_b3b708f3-2c56-4866-86c3-64459e1cc1cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_b3b708f3-2c56-4866-86c3-64459e1cc1cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_a1ac03f5-df26-4ae9-a788-768287af0e61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_a1ac03f5-df26-4ae9-a788-768287af0e61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_f98aadf5-b3a8-466c-974b-9e1d7b70c51b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_us-gaap_SecuredDebtMember_f98aadf5-b3a8-466c-974b-9e1d7b70c51b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_f978ccad-c456-4359-904c-9cff8cb5c30e" xlink:href="sui-20210331.xsd#sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_f978ccad-c456-4359-904c-9cff8cb5c30e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_81584523-b898-49e4-83d3-b1d08a45b8d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_us-gaap_LineOfCreditMember_81584523-b898-49e4-83d3-b1d08a45b8d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PreferredEquityMandatorilyRedeemableMember_8704f7ee-6f34-47f5-af5e-c565489c9c57" xlink:href="sui-20210331.xsd#sui_PreferredEquityMandatorilyRedeemableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_781e0c2e-5aa6-48df-87b9-396c4efed2d9" xlink:to="loc_sui_PreferredEquityMandatorilyRedeemableMember_8704f7ee-6f34-47f5-af5e-c565489c9c57" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeCollateralizedTermLoansDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCreditNarrativeCollateralizedTermLoansDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeCollateralizedTermLoansDetails" xlink:type="extended" id="i9da225448b6e4c959f6966a1862415b8_DebtAndLinesOfCreditNarrativeCollateralizedTermLoansDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_040ffa85-262b-4a2b-8889-d06f38fc3846" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_040ffa85-262b-4a2b-8889-d06f38fc3846" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_5e31818d-6772-4fa2-a0e2-b933db33ebdd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_5e31818d-6772-4fa2-a0e2-b933db33ebdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_aeeb0ef1-3b82-4f3f-8c5a-6c08b10e434c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_aeeb0ef1-3b82-4f3f-8c5a-6c08b10e434c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofRealEstateUnitsReleased_8f52235a-c71d-40d1-8c65-9838cffa62c2" xlink:href="sui-20210331.xsd#sui_NumberofRealEstateUnitsReleased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_NumberofRealEstateUnitsReleased_8f52235a-c71d-40d1-8c65-9838cffa62c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_9403744f-8a8e-448c-8d34-725e805b24a7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_9403744f-8a8e-448c-8d34-725e805b24a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_7c0f16e2-324c-4e40-b51a-414e2d0df22e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_7c0f16e2-324c-4e40-b51a-414e2d0df22e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_51833dd2-2238-4959-b09b-13cdf7fd1448" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentTerm_51833dd2-2238-4959-b09b-13cdf7fd1448" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_17218daf-9635-465d-baea-b266e563c034" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_17218daf-9635-465d-baea-b266e563c034" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_4dfb3e02-e763-43d0-b29a-eab008d203d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_4dfb3e02-e763-43d0-b29a-eab008d203d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_03af40fc-9577-42b9-9d6e-c6b9662658fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_03af40fc-9577-42b9-9d6e-c6b9662658fc" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfUnitsInRealEstateProperty_acd14828-be29-4506-ba82-ddc9a9bbf047" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfUnitsInRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_NumberOfUnitsInRealEstateProperty_acd14828-be29-4506-ba82-ddc9a9bbf047" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_d9ac4350-a4b3-4b76-a199-0e874712f4a7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_d9ac4350-a4b3-4b76-a199-0e874712f4a7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Debtweightedaveragetomaturitylength_20dbfdf4-583e-4a59-8a77-a5dfb2941331" xlink:href="sui-20210331.xsd#sui_Debtweightedaveragetomaturitylength"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_Debtweightedaveragetomaturitylength_20dbfdf4-583e-4a59-8a77-a5dfb2941331" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_01da36ed-ec0b-494d-b848-81fe862cc694" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_SecuredDebt_01da36ed-ec0b-494d-b848-81fe862cc694" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_5c7020c8-0bbc-4ca3-94d0-b8464cef5019" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_dei_DocumentPeriodEndDate_5c7020c8-0bbc-4ca3-94d0-b8464cef5019" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DebtInstrumentNumberOfPropertiesSecuringDebtInstument_5e8b3cf6-c1ef-4c5b-a546-94357077287d" xlink:href="sui-20210331.xsd#sui_DebtInstrumentNumberOfPropertiesSecuringDebtInstument"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_DebtInstrumentNumberOfPropertiesSecuringDebtInstument_5e8b3cf6-c1ef-4c5b-a546-94357077287d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental_ec752d26-2d6a-4e36-a98c-dd295532c036" xlink:href="sui-20210331.xsd#sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental_ec752d26-2d6a-4e36-a98c-dd295532c036" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_cb3c7a2a-751d-4b7b-938c-ab27c2d53876" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_cb3c7a2a-751d-4b7b-938c-ab27c2d53876" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_1db34b81-4616-44e9-9a16-fffc6d4e7b58" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_1db34b81-4616-44e9-9a16-fffc6d4e7b58" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfCollateralizedTermLoans_51fed81b-a8b2-446a-80bc-dfe133657c1c" xlink:href="sui-20210331.xsd#sui_NumberOfCollateralizedTermLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_sui_NumberOfCollateralizedTermLoans_51fed81b-a8b2-446a-80bc-dfe133657c1c" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9e98269a-7a7b-4ff8-b77f-dd0b1798455b" xlink:to="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_38e31611-b6a1-486c-89fb-e1c23700ff05" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:to="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_38e31611-b6a1-486c-89fb-e1c23700ff05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_38e31611-b6a1-486c-89fb-e1c23700ff05_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_38e31611-b6a1-486c-89fb-e1c23700ff05" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_38e31611-b6a1-486c-89fb-e1c23700ff05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_4a65af0e-a7f2-4919-8d34-fd1d6dc82342" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_38e31611-b6a1-486c-89fb-e1c23700ff05" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_4a65af0e-a7f2-4919-8d34-fd1d6dc82342" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PropertiessecuringdebtMember_648592fa-7088-4f67-99c4-77505446aacf" xlink:href="sui-20210331.xsd#sui_PropertiessecuringdebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_4a65af0e-a7f2-4919-8d34-fd1d6dc82342" xlink:to="loc_sui_PropertiessecuringdebtMember_648592fa-7088-4f67-99c4-77505446aacf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_417f94e1-cae9-4ffc-866c-57acc9a4a959" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_e013dd0a-2f64-41d3-8f88-9cb26e9ef62f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_417f94e1-cae9-4ffc-866c-57acc9a4a959" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_4c6fdb8f-a218-4278-9bd0-77822ec8b1cb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_417f94e1-cae9-4ffc-866c-57acc9a4a959" xlink:to="loc_us-gaap_SecuredDebtMember_4c6fdb8f-a218-4278-9bd0-77822ec8b1cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_28c33b06-392a-4599-a759-23c5f12fb463" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_417f94e1-cae9-4ffc-866c-57acc9a4a959" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_28c33b06-392a-4599-a759-23c5f12fb463" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_c522f8a3-f2f0-4929-a423-d3a6fc2a7dfe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_417f94e1-cae9-4ffc-866c-57acc9a4a959" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_c522f8a3-f2f0-4929-a423-d3a6fc2a7dfe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_aca4db16-ec5b-4761-87f3-38d1828194b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:to="loc_us-gaap_DebtInstrumentAxis_aca4db16-ec5b-4761-87f3-38d1828194b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_aca4db16-ec5b-4761-87f3-38d1828194b2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_aca4db16-ec5b-4761-87f3-38d1828194b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_aca4db16-ec5b-4761-87f3-38d1828194b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8a7dd336-fc9f-47ba-8327-d6eb145d3a82" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_aca4db16-ec5b-4761-87f3-38d1828194b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8a7dd336-fc9f-47ba-8327-d6eb145d3a82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CollateralizedTermLoan1Member_66aacc0f-2c0c-46ad-96dc-ae980f826a79" xlink:href="sui-20210331.xsd#sui_CollateralizedTermLoan1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a7dd336-fc9f-47ba-8327-d6eb145d3a82" xlink:to="loc_sui_CollateralizedTermLoan1Member_66aacc0f-2c0c-46ad-96dc-ae980f826a79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CollateralizedTermLoan2Member_8c1339ca-57e3-4a0f-b6ad-2376dc0de4a9" xlink:href="sui-20210331.xsd#sui_CollateralizedTermLoan2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a7dd336-fc9f-47ba-8327-d6eb145d3a82" xlink:to="loc_sui_CollateralizedTermLoan2Member_8c1339ca-57e3-4a0f-b6ad-2376dc0de4a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CollateralizedTermLoan3Member_e7e39a06-8e97-4b1b-b8d2-a4bf5ec2cdbd" xlink:href="sui-20210331.xsd#sui_CollateralizedTermLoan3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a7dd336-fc9f-47ba-8327-d6eb145d3a82" xlink:to="loc_sui_CollateralizedTermLoan3Member_e7e39a06-8e97-4b1b-b8d2-a4bf5ec2cdbd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3be2123f-74ff-4adb-a77f-dae18e934ac8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3be2123f-74ff-4adb-a77f-dae18e934ac8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3be2123f-74ff-4adb-a77f-dae18e934ac8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3be2123f-74ff-4adb-a77f-dae18e934ac8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3be2123f-74ff-4adb-a77f-dae18e934ac8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_de73fbff-816d-4b9d-845d-00e4d9b269aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3be2123f-74ff-4adb-a77f-dae18e934ac8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_de73fbff-816d-4b9d-845d-00e4d9b269aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMember_72908793-0d9f-45bc-b4f9-cee5cdd28c5d" xlink:href="sui-20210331.xsd#sui_SafeHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_de73fbff-816d-4b9d-845d-00e4d9b269aa" xlink:to="loc_sui_SafeHarborMember_72908793-0d9f-45bc-b4f9-cee5cdd28c5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_0e8c1d22-f21d-4208-b52a-3fc7d89fa493" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30e97fed-2e61-4afc-9cef-bb755c612e39" xlink:to="loc_us-gaap_CreditFacilityAxis_0e8c1d22-f21d-4208-b52a-3fc7d89fa493" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_0e8c1d22-f21d-4208-b52a-3fc7d89fa493_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_0e8c1d22-f21d-4208-b52a-3fc7d89fa493" xlink:to="loc_us-gaap_CreditFacilityDomain_0e8c1d22-f21d-4208-b52a-3fc7d89fa493_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c52595fc-7e95-4880-8f03-203766aee259" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_0e8c1d22-f21d-4208-b52a-3fc7d89fa493" xlink:to="loc_us-gaap_CreditFacilityDomain_c52595fc-7e95-4880-8f03-203766aee259" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_3c981db4-1f2d-44c6-b0c8-0a44acb9f7ea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_c52595fc-7e95-4880-8f03-203766aee259" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_3c981db4-1f2d-44c6-b0c8-0a44acb9f7ea" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeAspenPreferredOPUnitsandSeriesB3preferredOPunitsDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCreditNarrativeAspenPreferredOPUnitsandSeriesB3preferredOPunitsDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeAspenPreferredOPUnitsandSeriesB3preferredOPunitsDetails" xlink:type="extended" id="i986be5457ab34b5f83b3cb27747ab224_DebtAndLinesOfCreditNarrativeAspenPreferredOPUnitsandSeriesB3preferredOPunitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_8cd79b97-eeda-4461-a6f8-8a9bed531332" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_8cd79b97-eeda-4461-a6f8-8a9bed531332" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments_a7256e04-d50d-46ce-993b-497bce3666d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments_a7256e04-d50d-46ce-993b-497bce3666d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_b75eaa8e-dfb6-4d30-870d-7ad7df435e99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_b75eaa8e-dfb6-4d30-870d-7ad7df435e99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_3cb95d9d-a67e-4145-a0c6-dc0461ccb5f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_3cb95d9d-a67e-4145-a0c6-dc0461ccb5f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold_c8ebc03b-62ee-462d-87e4-ab2cf472d062" xlink:href="sui-20210331.xsd#sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold_c8ebc03b-62ee-462d-87e4-ab2cf472d062" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_d71301d2-d02b-48f9-a330-79f6a798b386" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_d71301d2-d02b-48f9-a330-79f6a798b386" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_a45d42ac-e358-4bf4-9df3-d77c76154252" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_a45d42ac-e358-4bf4-9df3-d77c76154252" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityRedemptionPricePerShareIncludingAccruedandUnpaidDividends_6db75b10-35e6-4253-a9fe-785ef12929f0" xlink:href="sui-20210331.xsd#sui_TemporaryEquityRedemptionPricePerShareIncludingAccruedandUnpaidDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_sui_TemporaryEquityRedemptionPricePerShareIncludingAccruedandUnpaidDividends_6db75b10-35e6-4253-a9fe-785ef12929f0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_7046dfe6-2bd3-462c-b239-b571683a4536" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_7046dfe6-2bd3-462c-b239-b571683a4536" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionValueofSharesIssued_41a8ab43-1870-43a4-a686-a9868db9e6be" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionValueofSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionValueofSharesIssued_41a8ab43-1870-43a4-a686-a9868db9e6be" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionRateOfReturn_bc1782d3-357e-41fa-9729-1030b08f07fb" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionRateOfReturn"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionRateOfReturn_bc1782d3-357e-41fa-9729-1030b08f07fb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_a2ba061b-4b4d-4f69-95f4-8b8a8a77974f" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_a2ba061b-4b4d-4f69-95f4-8b8a8a77974f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_601e449f-345e-4e7a-bf48-8d6b68e4b7e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsAmount_601e449f-345e-4e7a-bf48-8d6b68e4b7e1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_03a017fe-f79c-4a5d-a02e-b0229884effc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6473a538-5a07-4890-9d95-3e6ba4bc174d" xlink:to="loc_us-gaap_DebtInstrumentTable_03a017fe-f79c-4a5d-a02e-b0229884effc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_03a017fe-f79c-4a5d-a02e-b0229884effc" xlink:to="loc_us-gaap_StatementClassOfStockAxis_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff" xlink:to="loc_us-gaap_ClassOfStockDomain_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_bc03bdfa-ba93-484e-ab51-1016838a0de4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_bc6d9e87-4d91-4ed5-8924-19d09bbeb8ff" xlink:to="loc_us-gaap_ClassOfStockDomain_bc03bdfa-ba93-484e-ab51-1016838a0de4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesB3PreferredOPUnitsMember_00470987-5592-4bb5-a019-3f1be8a81e58" xlink:href="sui-20210331.xsd#sui_SeriesB3PreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_bc03bdfa-ba93-484e-ab51-1016838a0de4" xlink:to="loc_sui_SeriesB3PreferredOPUnitsMember_00470987-5592-4bb5-a019-3f1be8a81e58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_fb93b596-f7bb-4687-81a3-b082deadb988" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_03a017fe-f79c-4a5d-a02e-b0229884effc" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_fb93b596-f7bb-4687-81a3-b082deadb988" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_fb93b596-f7bb-4687-81a3-b082deadb988_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_fb93b596-f7bb-4687-81a3-b082deadb988" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_fb93b596-f7bb-4687-81a3-b082deadb988_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_e4e19141-0b5c-4f3c-8f4a-e4a10cc1755b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_fb93b596-f7bb-4687-81a3-b082deadb988" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_e4e19141-0b5c-4f3c-8f4a-e4a10cc1755b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PreferredEquityMandatorilyRedeemableMember_97ab3cc9-447f-418d-9d2f-42bc6dda4fef" xlink:href="sui-20210331.xsd#sui_PreferredEquityMandatorilyRedeemableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e4e19141-0b5c-4f3c-8f4a-e4a10cc1755b" xlink:to="loc_sui_PreferredEquityMandatorilyRedeemableMember_97ab3cc9-447f-418d-9d2f-42bc6dda4fef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_f8f5294d-7ba5-410b-a1c7-6b201fa7c772" xlink:href="sui-20210331.xsd#sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e4e19141-0b5c-4f3c-8f4a-e4a10cc1755b" xlink:to="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_f8f5294d-7ba5-410b-a1c7-6b201fa7c772" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesB3PreferredOPUnitsMember_e4462623-1ef0-4647-91cb-a741193e823f" xlink:href="sui-20210331.xsd#sui_SeriesB3PreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e4e19141-0b5c-4f3c-8f4a-e4a10cc1755b" xlink:to="loc_sui_SeriesB3PreferredOPUnitsMember_e4462623-1ef0-4647-91cb-a741193e823f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7d02d97b-6c41-46a3-aee1-480a2a2972e3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_03a017fe-f79c-4a5d-a02e-b0229884effc" xlink:to="loc_us-gaap_DebtInstrumentAxis_7d02d97b-6c41-46a3-aee1-480a2a2972e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7d02d97b-6c41-46a3-aee1-480a2a2972e3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7d02d97b-6c41-46a3-aee1-480a2a2972e3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7d02d97b-6c41-46a3-aee1-480a2a2972e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_0892bb99-af1c-40b1-ace9-fd8ee55cc42f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7d02d97b-6c41-46a3-aee1-480a2a2972e3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_0892bb99-af1c-40b1-ace9-fd8ee55cc42f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member_7284f932-245c-41b8-86b5-f82acb3daae3" xlink:href="sui-20210331.xsd#sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_0892bb99-af1c-40b1-ace9-fd8ee55cc42f" xlink:to="loc_sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member_7284f932-245c-41b8-86b5-f82acb3daae3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeLineofCreditDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#DebtAndLinesOfCreditNarrativeLineofCreditDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/DebtAndLinesOfCreditNarrativeLineofCreditDetails" xlink:type="extended" id="i1c354df0a753454aaa392ef3e0d7af98_DebtAndLinesOfCreditNarrativeLineofCreditDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_a87cab45-657e-419e-a2e9-6fe4953ddf22" xlink:href="sui-20210331.xsd#sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_FinancialInstrumentsSubjecttoMandatoryRedemptionTerm_a87cab45-657e-419e-a2e9-6fe4953ddf22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_43b77460-dbea-4c60-a61d-dbba329d1d9a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_43b77460-dbea-4c60-a61d-dbba329d1d9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_799daf6b-2a67-40af-8657-527f374611b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_799daf6b-2a67-40af-8657-527f374611b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_29f8e72f-00d2-4c5f-8b00-79f554be90a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_29f8e72f-00d2-4c5f-8b00-79f554be90a2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LineOfCreditFacilityAdditionalBorrowingCapacity_55ba3c1f-d07b-409e-b1d0-6c4157d9454e" xlink:href="sui-20210331.xsd#sui_LineOfCreditFacilityAdditionalBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_LineOfCreditFacilityAdditionalBorrowingCapacity_55ba3c1f-d07b-409e-b1d0-6c4157d9454e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_9a722f4a-540e-4174-b397-7fc37e40ca56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_9a722f4a-540e-4174-b397-7fc37e40ca56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtPercentageBearingVariableInterestRate_9a162157-7a07-4514-aaef-7e37870f6ff7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtPercentageBearingVariableInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LongTermDebtPercentageBearingVariableInterestRate_9a162157-7a07-4514-aaef-7e37870f6ff7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_c9f2f787-5744-447e-9219-01c31a83b696" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LongTermDebt_c9f2f787-5744-447e-9219-01c31a83b696" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_fe6e32ac-64f1-4bf6-88f0-e97fae3ce62d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_fe6e32ac-64f1-4bf6-88f0-e97fae3ce62d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_b0b14481-77aa-417c-a590-852a17d28083" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LineOfCredit_b0b14481-77aa-417c-a590-852a17d28083" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_46786e9c-a9f9-4834-8be4-af2aadc1062e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_46786e9c-a9f9-4834-8be4-af2aadc1062e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_7ad3865e-7a51-49a0-b1d7-95ba33d4b91f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_7ad3865e-7a51-49a0-b1d7-95ba33d4b91f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_dab6724f-413d-4b36-8b1a-d8f8b3ad0f93" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_dab6724f-413d-4b36-8b1a-d8f8b3ad0f93" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_51f5e22c-f97d-4fb2-9f9b-bda33fa856f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_51f5e22c-f97d-4fb2-9f9b-bda33fa856f7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_17d1f813-674c-4aa7-bd21-503edcb4d3c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_17d1f813-674c-4aa7-bd21-503edcb4d3c0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Debtweightedaveragetomaturitylength_43d47ceb-5b41-4bcb-b656-97821c8f635c" xlink:href="sui-20210331.xsd#sui_Debtweightedaveragetomaturitylength"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_Debtweightedaveragetomaturitylength_43d47ceb-5b41-4bcb-b656-97821c8f635c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofRealEstateUnitsReleased_b5cdb2bf-4c2e-497b-a1fb-ea22a5715215" xlink:href="sui-20210331.xsd#sui_NumberofRealEstateUnitsReleased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_NumberofRealEstateUnitsReleased_b5cdb2bf-4c2e-497b-a1fb-ea22a5715215" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleNotesPayable_637b9500-497a-4bfd-bce8-e2649d69794b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleNotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_ConvertibleNotesPayable_637b9500-497a-4bfd-bce8-e2649d69794b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_92a73fe4-3a25-4e1c-b7c4-26cf7681a6dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_92a73fe4-3a25-4e1c-b7c4-26cf7681a6dd" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_a018e557-ea22-4822-922e-ee3ca9653cbb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_a018e557-ea22-4822-922e-ee3ca9653cbb" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold_1a71aa6d-e00f-446e-8ff9-7cc87f58b6be" xlink:href="sui-20210331.xsd#sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_DebtInstrumentConvertiblePercentOfAmountByWhichTheMarketPriceOfCommonStockExceedsThreshold_1a71aa6d-e00f-446e-8ff9-7cc87f58b6be" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_3423a956-0712-411f-a704-31c3f6a1caa4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_3423a956-0712-411f-a704-31c3f6a1caa4" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments_2e3f2845-1c57-4c4e-92ed-b457e89f20d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_DebtInstrumentConvertibleNumberOfEquityInstruments_2e3f2845-1c57-4c4e-92ed-b457e89f20d3" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_9dd07b9b-a42a-4fe7-972f-554e1b876172" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_9dd07b9b-a42a-4fe7-972f-554e1b876172" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental_a28d066d-87f5-44fc-b0ee-786ff03fb8a7" xlink:href="sui-20210331.xsd#sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_sui_LineOfCreditFacilityMaximumBorrowingCapacityIncremental_a28d066d-87f5-44fc-b0ee-786ff03fb8a7" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_7b784396-f8e6-4d6b-b19c-1f1bafb0ecb3" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_74a45918-a2b7-4f62-aede-924ef571634a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_dei_LegalEntityAxis_74a45918-a2b7-4f62-aede-924ef571634a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_74a45918-a2b7-4f62-aede-924ef571634a_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_74a45918-a2b7-4f62-aede-924ef571634a" xlink:to="loc_dei_EntityDomain_74a45918-a2b7-4f62-aede-924ef571634a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_06515a88-447c-4a2d-b09b-29e6b3a7a900" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_74a45918-a2b7-4f62-aede-924ef571634a" xlink:to="loc_dei_EntityDomain_06515a88-447c-4a2d-b09b-29e6b3a7a900" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GTSCMember_3eee6414-5eb3-4b61-a19f-abdc39a12082" xlink:href="sui-20210331.xsd#sui_GTSCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_06515a88-447c-4a2d-b09b-29e6b3a7a900" xlink:to="loc_sui_GTSCMember_3eee6414-5eb3-4b61-a19f-abdc39a12082" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SungeniaJVMember_4a4fe6c7-53e9-4b75-bd1e-66fd361f7666" xlink:href="sui-20210331.xsd#sui_SungeniaJVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_06515a88-447c-4a2d-b09b-29e6b3a7a900" xlink:to="loc_sui_SungeniaJVMember_4a4fe6c7-53e9-4b75-bd1e-66fd361f7666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a5130c0c-5f9a-4ac2-be20-c4266d9ece26" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a5130c0c-5f9a-4ac2-be20-c4266d9ece26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_a5130c0c-5f9a-4ac2-be20-c4266d9ece26_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a5130c0c-5f9a-4ac2-be20-c4266d9ece26" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_a5130c0c-5f9a-4ac2-be20-c4266d9ece26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_fabe4dcf-4ee8-44db-8926-77707f56d202" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a5130c0c-5f9a-4ac2-be20-c4266d9ece26" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_fabe4dcf-4ee8-44db-8926-77707f56d202" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_GTSCMember_bd90ba93-7add-4840-b50c-2f71a09208e8" xlink:href="sui-20210331.xsd#sui_GTSCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fabe4dcf-4ee8-44db-8926-77707f56d202" xlink:to="loc_sui_GTSCMember_bd90ba93-7add-4840-b50c-2f71a09208e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RezPlotMember_4ccf123c-bdee-4fed-b80d-04892002a6de" xlink:href="sui-20210331.xsd#sui_RezPlotMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fabe4dcf-4ee8-44db-8926-77707f56d202" xlink:to="loc_sui_RezPlotMember_4ccf123c-bdee-4fed-b80d-04892002a6de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SungeniaJVMember_ff8b650a-c089-4713-8aa5-f103e226c1fb" xlink:href="sui-20210331.xsd#sui_SungeniaJVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fabe4dcf-4ee8-44db-8926-77707f56d202" xlink:to="loc_sui_SungeniaJVMember_ff8b650a-c089-4713-8aa5-f103e226c1fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a769cb66-fd1e-498f-924d-e1de7187276c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_srt_RangeAxis_a769cb66-fd1e-498f-924d-e1de7187276c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a769cb66-fd1e-498f-924d-e1de7187276c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a769cb66-fd1e-498f-924d-e1de7187276c" xlink:to="loc_srt_RangeMember_a769cb66-fd1e-498f-924d-e1de7187276c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b1e2a8a6-77b3-4593-83a4-58197b2e6954" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a769cb66-fd1e-498f-924d-e1de7187276c" xlink:to="loc_srt_RangeMember_b1e2a8a6-77b3-4593-83a4-58197b2e6954" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_52ec69d2-1478-4c83-a0c4-6cae69f9d077" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b1e2a8a6-77b3-4593-83a4-58197b2e6954" xlink:to="loc_srt_MinimumMember_52ec69d2-1478-4c83-a0c4-6cae69f9d077" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b2acf519-d76d-42ae-a737-efe3d1f0f49b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b1e2a8a6-77b3-4593-83a4-58197b2e6954" xlink:to="loc_srt_MaximumMember_b2acf519-d76d-42ae-a737-efe3d1f0f49b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_85c1a9cd-04a8-4839-8c65-d07364423261" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_us-gaap_CreditFacilityAxis_85c1a9cd-04a8-4839-8c65-d07364423261" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_85c1a9cd-04a8-4839-8c65-d07364423261_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_85c1a9cd-04a8-4839-8c65-d07364423261" xlink:to="loc_us-gaap_CreditFacilityDomain_85c1a9cd-04a8-4839-8c65-d07364423261_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4310cc82-5108-4069-a3ca-332ccdb90fdf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_85c1a9cd-04a8-4839-8c65-d07364423261" xlink:to="loc_us-gaap_CreditFacilityDomain_4310cc82-5108-4069-a3ca-332ccdb90fdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2a8a746b-f447-4cd2-8fe9-b2fcabf58431" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4310cc82-5108-4069-a3ca-332ccdb90fdf" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2a8a746b-f447-4cd2-8fe9-b2fcabf58431" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TermLoanMember_3cc11df6-17cb-4c24-bc87-bea717ed4088" xlink:href="sui-20210331.xsd#sui_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4310cc82-5108-4069-a3ca-332ccdb90fdf" xlink:to="loc_sui_TermLoanMember_3cc11df6-17cb-4c24-bc87-bea717ed4088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_133f68b3-1f1a-40b0-9bf3-c75d6b8dac47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4310cc82-5108-4069-a3ca-332ccdb90fdf" xlink:to="loc_us-gaap_LineOfCreditMember_133f68b3-1f1a-40b0-9bf3-c75d6b8dac47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_5af3820d-c166-4bf8-9560-fd534313f3df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_us-gaap_VariableRateAxis_5af3820d-c166-4bf8-9560-fd534313f3df" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_5af3820d-c166-4bf8-9560-fd534313f3df_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_5af3820d-c166-4bf8-9560-fd534313f3df" xlink:to="loc_us-gaap_VariableRateDomain_5af3820d-c166-4bf8-9560-fd534313f3df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_5af3820d-c166-4bf8-9560-fd534313f3df" xlink:to="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EurodollarMember_ad9b5d0a-8cda-413b-a1ec-6db297f714e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EurodollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:to="loc_us-gaap_EurodollarMember_ad9b5d0a-8cda-413b-a1ec-6db297f714e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrimeRateMember_b2013970-95d9-4bbc-bb4d-f96774a308d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrimeRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:to="loc_us-gaap_PrimeRateMember_b2013970-95d9-4bbc-bb4d-f96774a308d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_0d7e8698-62f4-4b92-81b3-b0822897516e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_0d7e8698-62f4-4b92-81b3-b0822897516e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_14149151-4d65-4437-8f54-3feb9cfa5640" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7a18d97c-d93c-4430-a99c-a25073103584" xlink:to="loc_us-gaap_BaseRateMember_14149151-4d65-4437-8f54-3feb9cfa5640" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1ef4ac2a-8f3c-4723-a33c-8199642e5e16" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1ef4ac2a-8f3c-4723-a33c-8199642e5e16" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1ef4ac2a-8f3c-4723-a33c-8199642e5e16_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1ef4ac2a-8f3c-4723-a33c-8199642e5e16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1ef4ac2a-8f3c-4723-a33c-8199642e5e16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1ef4ac2a-8f3c-4723-a33c-8199642e5e16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ARFacilityMember_cc744564-196f-49ff-aec2-7db14789d84c" xlink:href="sui-20210331.xsd#sui_ARFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_sui_ARFacilityMember_cc744564-196f-49ff-aec2-7db14789d84c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_a369cfc0-8aa2-4dcb-a5e0-cbc00cd8c4a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_us-gaap_LineOfCreditMember_a369cfc0-8aa2-4dcb-a5e0-cbc00cd8c4a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LineOfCreditManufacturedHomeFloorPlanFacilityMember_84eaaa58-975a-4d98-a524-ec42217b2c36" xlink:href="sui-20210331.xsd#sui_LineOfCreditManufacturedHomeFloorPlanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_sui_LineOfCreditManufacturedHomeFloorPlanFacilityMember_84eaaa58-975a-4d98-a524-ec42217b2c36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TermLoanMember_a405ae4f-6820-4b7e-aa55-a0f9ac214877" xlink:href="sui-20210331.xsd#sui_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_sui_TermLoanMember_a405ae4f-6820-4b7e-aa55-a0f9ac214877" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_d8669048-2bd6-4f29-ba51-2927f2a1da0d" xlink:href="sui-20210331.xsd#sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_sui_AspenSeriesB3PreferredOperatingPartnershipUnitsMember_d8669048-2bd6-4f29-ba51-2927f2a1da0d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_640f491f-39f4-405e-bfde-767e0122ead8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_db468954-ff9e-41d3-8515-2e733136a02b" xlink:to="loc_us-gaap_SecuredDebtMember_640f491f-39f4-405e-bfde-767e0122ead8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_7e8b5b78-043c-42d5-a733-bf74639ffaff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_7e8b5b78-043c-42d5-a733-bf74639ffaff" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7e8b5b78-043c-42d5-a733-bf74639ffaff_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_7e8b5b78-043c-42d5-a733-bf74639ffaff" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_7e8b5b78-043c-42d5-a733-bf74639ffaff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e0c6e826-9f0d-46de-b67b-fbfa28f0495a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_7e8b5b78-043c-42d5-a733-bf74639ffaff" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e0c6e826-9f0d-46de-b67b-fbfa28f0495a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMember_e0b21832-ac42-4ef3-93d7-0ef724d2a279" xlink:href="sui-20210331.xsd#sui_SafeHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e0c6e826-9f0d-46de-b67b-fbfa28f0495a" xlink:to="loc_sui_SafeHarborMember_e0b21832-ac42-4ef3-93d7-0ef724d2a279" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_8e60f481-7e94-4eaf-a7bb-63b8ac590953" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_aa4f34c9-ff5d-4aa2-9944-212f0cd33582" xlink:to="loc_us-gaap_DebtInstrumentAxis_8e60f481-7e94-4eaf-a7bb-63b8ac590953" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8e60f481-7e94-4eaf-a7bb-63b8ac590953_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_8e60f481-7e94-4eaf-a7bb-63b8ac590953" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8e60f481-7e94-4eaf-a7bb-63b8ac590953_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_408130da-4ddf-428a-be24-92451228d09e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_8e60f481-7e94-4eaf-a7bb-63b8ac590953" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_408130da-4ddf-428a-be24-92451228d09e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member_a0915946-0870-4f07-88e1-b2e34b194ba9" xlink:href="sui-20210331.xsd#sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_408130da-4ddf-428a-be24-92451228d09e" xlink:to="loc_sui_ConvertibleDebtAspenPreferredOpUnitsJanuary2024Member_a0915946-0870-4f07-88e1-b2e34b194ba9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TotalSungeniaDebtMember_e372ec01-36f0-4cdf-8f5e-211055de6d91" xlink:href="sui-20210331.xsd#sui_TotalSungeniaDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_408130da-4ddf-428a-be24-92451228d09e" xlink:to="loc_sui_TotalSungeniaDebtMember_e372ec01-36f0-4cdf-8f5e-211055de6d91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JVDebtAffiliatedEntityPortionMember_a31517b0-93b3-40a0-a408-79b3b5c7e192" xlink:href="sui-20210331.xsd#sui_JVDebtAffiliatedEntityPortionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_408130da-4ddf-428a-be24-92451228d09e" xlink:to="loc_sui_JVDebtAffiliatedEntityPortionMember_a31517b0-93b3-40a0-a408-79b3b5c7e192" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquity" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquity"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquity" xlink:type="extended" id="if71acc5e5c5b4980880fde4c0041c305_EquityandTemporaryEquity"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquityTables" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquityTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquityTables" xlink:type="extended" id="i38a32d6021754292ba2c9cfc4b28c2e3_EquityandTemporaryEquityTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquityNarrativeDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquityNarrativeDetails" xlink:type="extended" id="i0a00ddadc8594f0d927852619ce580f6_EquityandTemporaryEquityNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_505ac959-a6bb-484b-a36e-17047652061d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_505ac959-a6bb-484b-a36e-17047652061d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_1a172b9b-9b96-463c-940c-63ed5821e369" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_1a172b9b-9b96-463c-940c-63ed5821e369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_84ab8a62-8700-430c-9963-636b5b5a587b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_84ab8a62-8700-430c-9963-636b5b5a587b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividendsForTermOnePercentage_acc4a6ac-9156-40bc-8eae-7c0d477b2dc1" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividendsForTermOnePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_TemporaryEquityDividendsForTermOnePercentage_acc4a6ac-9156-40bc-8eae-7c0d477b2dc1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityEquityInterestsIssued_de4d70e2-324a-4c1b-b3ba-c3058243c3f0" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityEquityInterestsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_VariableInterestEntityEquityInterestsIssued_de4d70e2-324a-4c1b-b3ba-c3058243c3f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityEquityInterestsIssuedFloatingRate_46b06b5b-2edb-4231-b616-b34e5ab346a7" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityEquityInterestsIssuedFloatingRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_VariableInterestEntityEquityInterestsIssuedFloatingRate_46b06b5b-2edb-4231-b616-b34e5ab346a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6d31c23a-b610-425a-ada9-769358c5d866" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6d31c23a-b610-425a-ada9-769358c5d866" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement_21539d4b-4971-4e1c-9d4f-78a7234d16fe" xlink:href="sui-20210331.xsd#sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement_21539d4b-4971-4e1c-9d4f-78a7234d16fe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommissionMaximumPercentageofGrossSalesPricePerShareAccordingtoSalesAgreement_3c6bdd44-9816-4f7d-a95b-8de84aae5dc6" xlink:href="sui-20210331.xsd#sui_CommissionMaximumPercentageofGrossSalesPricePerShareAccordingtoSalesAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_CommissionMaximumPercentageofGrossSalesPricePerShareAccordingtoSalesAgreement_3c6bdd44-9816-4f7d-a95b-8de84aae5dc6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_ccc3109b-e966-4ef4-b1f7-fe41472df3b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_ccc3109b-e966-4ef4-b1f7-fe41472df3b8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased_7b7b794a-1cb6-4ccc-999e-1a60ed223464" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased_7b7b794a-1cb6-4ccc-999e-1a60ed223464" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_104c21ae-1cc7-46ec-91ba-9a3e7b563dcd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_104c21ae-1cc7-46ec-91ba-9a3e7b563dcd" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_869f70b5-dfd8-46b0-b210-2ad2db5c2a0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_869f70b5-dfd8-46b0-b210-2ad2db5c2a0e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_bdbefef0-3e15-43a3-a47a-ca61cdbbda74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_bdbefef0-3e15-43a3-a47a-ca61cdbbda74" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_096158b5-b38b-4e2e-a5ad-982cb0520b2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_096158b5-b38b-4e2e-a5ad-982cb0520b2d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareDeclared_5779b3d7-1294-44cf-b0a6-0e49aa6c0023" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareDeclared_5779b3d7-1294-44cf-b0a6-0e49aa6c0023" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_20bea552-1cd3-481d-8173-50f5db61770d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_20bea552-1cd3-481d-8173-50f5db61770d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_a54d8633-52d4-4e60-8b4a-8cedec48910b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_a54d8633-52d4-4e60-8b4a-8cedec48910b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityIssuancePrice_88f3c455-a2a9-48d7-b802-d5092a56482b" xlink:href="sui-20210331.xsd#sui_TemporaryEquityIssuancePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_TemporaryEquityIssuancePrice_88f3c455-a2a9-48d7-b802-d5092a56482b" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividendsForTermTwoPercentage_b1000f28-ae7b-4b80-96e2-756eaf316073" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividendsForTermTwoPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_TemporaryEquityDividendsForTermTwoPercentage_b1000f28-ae7b-4b80-96e2-756eaf316073" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_97ac090f-00ff-460b-b97a-507c6a965e58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_97ac090f-00ff-460b-b97a-507c6a965e58" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_f2e85984-f854-4839-8038-7ae220d19603" xlink:href="sui-20210331.xsd#sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_f2e85984-f854-4839-8038-7ae220d19603" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_5f55179d-8a45-4e8c-989e-2eede60361b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_5f55179d-8a45-4e8c-989e-2eede60361b7" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VariableInterestEntityEquityInterest_ebc6ef53-d94f-4b97-af7c-73f2b1b580a1" xlink:href="sui-20210331.xsd#sui_VariableInterestEntityEquityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_VariableInterestEntityEquityInterest_ebc6ef53-d94f-4b97-af7c-73f2b1b580a1" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireLimitedPartnershipInterests_79f80430-f41a-4704-b0e8-f13d21a36a73" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireLimitedPartnershipInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_PaymentsToAcquireLimitedPartnershipInterests_79f80430-f41a-4704-b0e8-f13d21a36a73" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestInLimitedPartnerships_7121ad8c-d1da-4df6-964d-37d4a7491562" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestInLimitedPartnerships"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_MinorityInterestInLimitedPartnerships_7121ad8c-d1da-4df6-964d-37d4a7491562" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SaleOfStockNumberOfSharesIssuedInTransactionDirect_6b884c30-40d4-4240-9b55-1dbda8a5235b" xlink:href="sui-20210331.xsd#sui_SaleOfStockNumberOfSharesIssuedInTransactionDirect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_SaleOfStockNumberOfSharesIssuedInTransactionDirect_6b884c30-40d4-4240-9b55-1dbda8a5235b" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SaleOfStockNumberOfSharesIssuedInTransactionForwardEquitySales_59d5d7f3-6910-440e-a871-c0637ec0d594" xlink:href="sui-20210331.xsd#sui_SaleOfStockNumberOfSharesIssuedInTransactionForwardEquitySales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_SaleOfStockNumberOfSharesIssuedInTransactionForwardEquitySales_59d5d7f3-6910-440e-a871-c0637ec0d594" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NetProceedsFromForwardEquityOffering_dc1c63f4-b505-4ae4-a653-d0a0f1450b7f" xlink:href="sui-20210331.xsd#sui_NetProceedsFromForwardEquityOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_sui_NetProceedsFromForwardEquityOffering_dc1c63f4-b505-4ae4-a653-d0a0f1450b7f" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_d9b79bcb-9ce0-4baa-85c1-63a65835fd0e" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_9141f08a-ba4c-4511-a13b-1893a9dc5c26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_9141f08a-ba4c-4511-a13b-1893a9dc5c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9141f08a-ba4c-4511-a13b-1893a9dc5c26_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9141f08a-ba4c-4511-a13b-1893a9dc5c26" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9141f08a-ba4c-4511-a13b-1893a9dc5c26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9141f08a-ba4c-4511-a13b-1893a9dc5c26" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_JensenCommunitiesDomain_17f06601-16ff-4d5c-8858-cccfa9bbb59b" xlink:href="sui-20210331.xsd#sui_JensenCommunitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:to="loc_sui_JensenCommunitiesDomain_17f06601-16ff-4d5c-8858-cccfa9bbb59b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ForestSpringsMember_b3392917-435a-41a7-b4c7-6c20790b2059" xlink:href="sui-20210331.xsd#sui_ForestSpringsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:to="loc_sui_ForestSpringsMember_b3392917-435a-41a7-b4c7-6c20790b2059" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborRybovichMember_e52425e0-0d5e-4fe4-95d3-24dc2dadb783" xlink:href="sui-20210331.xsd#sui_SafeHarborRybovichMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:to="loc_sui_SafeHarborRybovichMember_e52425e0-0d5e-4fe4-95d3-24dc2dadb783" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMember_a0044d1c-a8a9-40ad-b67c-38f3a35c9490" xlink:href="sui-20210331.xsd#sui_SafeHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0d6655f6-d0c4-4c88-bd66-5502557d9a32" xlink:to="loc_sui_SafeHarborMember_a0044d1c-a8a9-40ad-b67c-38f3a35c9490" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_faefe262-4d28-44c3-9fdb-1b830873f175" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_srt_StatementScenarioAxis_faefe262-4d28-44c3-9fdb-1b830873f175" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_faefe262-4d28-44c3-9fdb-1b830873f175_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_faefe262-4d28-44c3-9fdb-1b830873f175" xlink:to="loc_srt_ScenarioUnspecifiedDomain_faefe262-4d28-44c3-9fdb-1b830873f175_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_d71b3d2c-5739-4882-b5b7-943bf9e61577" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_faefe262-4d28-44c3-9fdb-1b830873f175" xlink:to="loc_srt_ScenarioUnspecifiedDomain_d71b3d2c-5739-4882-b5b7-943bf9e61577" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_37517e85-a614-49e3-842b-92fba1a42b1d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_d71b3d2c-5739-4882-b5b7-943bf9e61577" xlink:to="loc_srt_ScenarioForecastMember_37517e85-a614-49e3-842b-92fba1a42b1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_0f91f13b-2a0e-46cd-9c81-78a7d6c41a46" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NGSunLLCMember_66e2311d-ddd8-416a-a11c-5cf105cb14e9" xlink:href="sui-20210331.xsd#sui_NGSunLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:to="loc_sui_NGSunLLCMember_66e2311d-ddd8-416a-a11c-5cf105cb14e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SunNGRVResortsMember_9b607fa3-a9e0-4290-92b1-fe2cc5ad434c" xlink:href="sui-20210331.xsd#sui_SunNGRVResortsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:to="loc_sui_SunNGRVResortsMember_9b607fa3-a9e0-4290-92b1-fe2cc5ad434c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NGSunWhitewaterMember_992135bd-a2a2-4172-8ed4-61b1f02d02cf" xlink:href="sui-20210331.xsd#sui_NGSunWhitewaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:to="loc_sui_NGSunWhitewaterMember_992135bd-a2a2-4172-8ed4-61b1f02d02cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SunMenifeeMember_9947f8da-dc4b-4f7a-95b9-ecea304b93d2" xlink:href="sui-20210331.xsd#sui_SunMenifeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_9d890852-512f-4c60-a395-eafd454c52a3" xlink:to="loc_sui_SunMenifeeMember_9947f8da-dc4b-4f7a-95b9-ecea304b93d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_c025a256-c644-4827-8640-f3eb2fee740e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_c025a256-c644-4827-8640-f3eb2fee740e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_c025a256-c644-4827-8640-f3eb2fee740e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_c025a256-c644-4827-8640-f3eb2fee740e" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_c025a256-c644-4827-8640-f3eb2fee740e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_40af76b8-d7a8-432d-bfa4-7db0e357cfb2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_c025a256-c644-4827-8640-f3eb2fee740e" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_40af76b8-d7a8-432d-bfa4-7db0e357cfb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_033f9740-5125-4cb8-86b5-aafe1509e0fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_40af76b8-d7a8-432d-bfa4-7db0e357cfb2" xlink:to="loc_us-gaap_CommonStockMember_033f9740-5125-4cb8-86b5-aafe1509e0fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_553b398d-1d64-4442-9695-b99930eb9861" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_dei_LegalEntityAxis_553b398d-1d64-4442-9695-b99930eb9861" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_553b398d-1d64-4442-9695-b99930eb9861_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_553b398d-1d64-4442-9695-b99930eb9861" xlink:to="loc_dei_EntityDomain_553b398d-1d64-4442-9695-b99930eb9861_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_c1c87bfe-c983-40ed-ba6e-cd1e8a808659" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_553b398d-1d64-4442-9695-b99930eb9861" xlink:to="loc_dei_EntityDomain_c1c87bfe-c983-40ed-ba6e-cd1e8a808659" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NGSunWhitewaterMember_78f252a1-7e16-4949-834b-ddcf63fb7369" xlink:href="sui-20210331.xsd#sui_NGSunWhitewaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_c1c87bfe-c983-40ed-ba6e-cd1e8a808659" xlink:to="loc_sui_NGSunWhitewaterMember_78f252a1-7e16-4949-834b-ddcf63fb7369" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SunNGRVResortsMember_9ba356d5-e463-4710-9f36-03005a63d31c" xlink:href="sui-20210331.xsd#sui_SunNGRVResortsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_c1c87bfe-c983-40ed-ba6e-cd1e8a808659" xlink:to="loc_sui_SunNGRVResortsMember_9ba356d5-e463-4710-9f36-03005a63d31c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_9cd28d36-559e-47fb-a799-6428d32df7b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_9cd28d36-559e-47fb-a799-6428d32df7b9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_9cd28d36-559e-47fb-a799-6428d32df7b9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_9cd28d36-559e-47fb-a799-6428d32df7b9" xlink:to="loc_us-gaap_EquityComponentDomain_9cd28d36-559e-47fb-a799-6428d32df7b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_9cd28d36-559e-47fb-a799-6428d32df7b9" xlink:to="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_bf5fdaf5-0d91-44e8-a147-504c8cfd718c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:to="loc_us-gaap_CommonStockMember_bf5fdaf5-0d91-44e8-a147-504c8cfd718c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredOpUnitsMember_ee3f356e-f6f9-4b8a-99af-785a70d3655e" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:to="loc_sui_SeriesA4PreferredOpUnitsMember_ee3f356e-f6f9-4b8a-99af-785a70d3655e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConversionofCommonOPUnitsMember_c7542759-0f3d-4543-8e9d-944b8e136800" xlink:href="sui-20210331.xsd#sui_ConversionofCommonOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:to="loc_sui_ConversionofCommonOPUnitsMember_c7542759-0f3d-4543-8e9d-944b8e136800" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA1PreferredOpUnitsMember_87fa5745-38a2-4b83-9420-a2437474861d" xlink:href="sui-20210331.xsd#sui_SeriesA1PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e827b148-da2e-4ea7-887b-e0101654720e" xlink:to="loc_sui_SeriesA1PreferredOpUnitsMember_87fa5745-38a2-4b83-9420-a2437474861d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityTransactionTypeAxis_ca6bd4d9-a93a-4470-a87b-4318a171a854" xlink:href="sui-20210331.xsd#sui_EquityTransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_sui_EquityTransactionTypeAxis_ca6bd4d9-a93a-4470-a87b-4318a171a854" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityTransactionTypeDomain_ca6bd4d9-a93a-4470-a87b-4318a171a854_default" xlink:href="sui-20210331.xsd#sui_EquityTransactionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_EquityTransactionTypeAxis_ca6bd4d9-a93a-4470-a87b-4318a171a854" xlink:to="loc_sui_EquityTransactionTypeDomain_ca6bd4d9-a93a-4470-a87b-4318a171a854_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_EquityTransactionTypeDomain_61e7b43f-b082-4b3f-a901-d2113e9ab98d" xlink:href="sui-20210331.xsd#sui_EquityTransactionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_EquityTransactionTypeAxis_ca6bd4d9-a93a-4470-a87b-4318a171a854" xlink:to="loc_sui_EquityTransactionTypeDomain_61e7b43f-b082-4b3f-a901-d2113e9ab98d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_3e3a08f7-8b44-458f-8187-d3dd36f08bc1" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_EquityTransactionTypeDomain_61e7b43f-b082-4b3f-a901-d2113e9ab98d" xlink:to="loc_sui_SeriesA4PreferredStockMember_3e3a08f7-8b44-458f-8187-d3dd36f08bc1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_e7632c47-a05d-4bb9-b56b-d5b0899f9a0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_EquityTransactionTypeDomain_61e7b43f-b082-4b3f-a901-d2113e9ab98d" xlink:to="loc_us-gaap_CommonStockMember_e7632c47-a05d-4bb9-b56b-d5b0899f9a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_dcf3f212-7ac8-4036-8559-62888e5f1749" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_EquityTransactionTypeDomain_61e7b43f-b082-4b3f-a901-d2113e9ab98d" xlink:to="loc_sui_CommonOpUnitsMember_dcf3f212-7ac8-4036-8559-62888e5f1749" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a4511c62-95cf-4704-8936-a1a2d6ea927c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a4511c62-95cf-4704-8936-a1a2d6ea927c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a4511c62-95cf-4704-8936-a1a2d6ea927c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a4511c62-95cf-4704-8936-a1a2d6ea927c" xlink:to="loc_us-gaap_ClassOfStockDomain_a4511c62-95cf-4704-8936-a1a2d6ea927c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a4511c62-95cf-4704-8936-a1a2d6ea927c" xlink:to="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesEPreferredOPUnitsDomain_808b2dcb-ac85-47b5-9092-afb036ef643e" xlink:href="sui-20210331.xsd#sui_SeriesEPreferredOPUnitsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesEPreferredOPUnitsDomain_808b2dcb-ac85-47b5-9092-afb036ef643e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesDPreferredOPUnitsMember_d89a7eee-c39a-4812-b1ee-1efb30fe47ce" xlink:href="sui-20210331.xsd#sui_SeriesDPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesDPreferredOPUnitsMember_d89a7eee-c39a-4812-b1ee-1efb30fe47ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_9ba820c9-38de-4a92-80a7-913fb6e21aef" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesA4PreferredStockMember_9ba820c9-38de-4a92-80a7-913fb6e21aef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_5a7ecec0-1a85-4431-8974-eaf676ce3ef2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_us-gaap_CommonStockMember_5a7ecec0-1a85-4431-8974-eaf676ce3ef2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_ca746cd5-4402-412b-a255-bcfa7527ded9" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_CommonOpUnitsMember_ca746cd5-4402-412b-a255-bcfa7527ded9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredOpUnitsMember_cb9261c7-c44e-4f4b-b487-699a29484303" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesA4PreferredOpUnitsMember_cb9261c7-c44e-4f4b-b487-699a29484303" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_69b31544-e574-4830-903a-92f792594ef2" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_69b31544-e574-4830-903a-92f792594ef2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesGPreferredOPUnitsMember_8c2afe14-e62f-4e27-809a-94f02f72e528" xlink:href="sui-20210331.xsd#sui_SeriesGPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesGPreferredOPUnitsMember_8c2afe14-e62f-4e27-809a-94f02f72e528" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesHPreferredOPUnitsMember_9c2ccb88-9b64-492e-a777-e4f31a31d7c8" xlink:href="sui-20210331.xsd#sui_SeriesHPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c6cbcf12-c1cd-40b7-a5e3-ee9c71200ac6" xlink:to="loc_sui_SeriesHPreferredOPUnitsMember_9c2ccb88-9b64-492e-a777-e4f31a31d7c8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_6c20dde3-f672-4e3f-ae75-913e9bc16552" xlink:to="loc_srt_RangeAxis_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6" xlink:to="loc_srt_RangeMember_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_88831b8d-8246-4ab2-a4a2-49ca181d5e90" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ebbacf3f-f4fe-41f6-a79a-99b53c90eea6" xlink:to="loc_srt_RangeMember_88831b8d-8246-4ab2-a4a2-49ca181d5e90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5bfff068-08a3-4986-bd29-82693ed0fae6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_88831b8d-8246-4ab2-a4a2-49ca181d5e90" xlink:to="loc_srt_MaximumMember_5bfff068-08a3-4986-bd29-82693ed0fae6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_33bf8aa4-e3a3-42ad-9334-a5db1dc124f5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_88831b8d-8246-4ab2-a4a2-49ca181d5e90" xlink:to="loc_srt_MinimumMember_33bf8aa4-e3a3-42ad-9334-a5db1dc124f5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquityConversionofStockDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquityConversionofStockDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquityConversionofStockDetails" xlink:type="extended" id="i9d7db47cccd1412b905fa7d2763f9480_EquityandTemporaryEquityConversionofStockDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividendsForTermTwoPercentage_ecdee4c8-0bf5-415e-9c2e-3c8be9335cac" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividendsForTermTwoPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_sui_TemporaryEquityDividendsForTermTwoPercentage_ecdee4c8-0bf5-415e-9c2e-3c8be9335cac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_5a42f0bf-d525-4faa-824f-b859e9cfc0a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_5a42f0bf-d525-4faa-824f-b859e9cfc0a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityIssuancePrice_1bd5b371-808b-4a28-a794-82e9930524a5" xlink:href="sui-20210331.xsd#sui_TemporaryEquityIssuancePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_sui_TemporaryEquityIssuancePrice_1bd5b371-808b-4a28-a794-82e9930524a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesIssued1_a43e940b-2afe-49a4-b118-328098b73970" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_ConversionOfStockSharesIssued1_a43e940b-2afe-49a4-b118-328098b73970" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_0980dec7-9ce8-46a0-b658-74bb1d9ac6f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_0980dec7-9ce8-46a0-b658-74bb1d9ac6f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_b9cf500e-2065-4424-87b1-72fe34027bda" xlink:href="sui-20210331.xsd#sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_b9cf500e-2065-4424-87b1-72fe34027bda" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentsJointVentures_61291437-ae01-4316-89ab-515dd202ff8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentsJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_RealEstateInvestmentsJointVentures_61291437-ae01-4316-89ab-515dd202ff8d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividendsForTermOnePercentage_b10823f8-3efc-4b9e-a3e4-f0d75a95ad08" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividendsForTermOnePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_sui_TemporaryEquityDividendsForTermOnePercentage_b10823f8-3efc-4b9e-a3e4-f0d75a95ad08" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_51488c5b-288d-47ac-86e0-f0e347804a27" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_51488c5b-288d-47ac-86e0-f0e347804a27" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConversionOfStockLineItems_f2b59d78-f16c-41af-a7e6-030738e84b55" xlink:to="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_7fad61a3-b325-4944-8db8-b952db96cd7d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_srt_StatementScenarioAxis_7fad61a3-b325-4944-8db8-b952db96cd7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_7fad61a3-b325-4944-8db8-b952db96cd7d_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_7fad61a3-b325-4944-8db8-b952db96cd7d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_7fad61a3-b325-4944-8db8-b952db96cd7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_590e5e56-c766-47d6-a7f6-ff042a2a3f26" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_7fad61a3-b325-4944-8db8-b952db96cd7d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_590e5e56-c766-47d6-a7f6-ff042a2a3f26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_6ecc4868-f513-488e-b7d1-659016782995" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_590e5e56-c766-47d6-a7f6-ff042a2a3f26" xlink:to="loc_srt_ScenarioForecastMember_6ecc4868-f513-488e-b7d1-659016782995" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_34dc4cde-8939-489a-87e8-f84933a243fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_us-gaap_StatementClassOfStockAxis_34dc4cde-8939-489a-87e8-f84933a243fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_34dc4cde-8939-489a-87e8-f84933a243fc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_34dc4cde-8939-489a-87e8-f84933a243fc" xlink:to="loc_us-gaap_ClassOfStockDomain_34dc4cde-8939-489a-87e8-f84933a243fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_34dc4cde-8939-489a-87e8-f84933a243fc" xlink:to="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesDPreferredOPUnitsMember_dca8a12e-302a-491c-ad7e-31d833fa4015" xlink:href="sui-20210331.xsd#sui_SeriesDPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_sui_SeriesDPreferredOPUnitsMember_dca8a12e-302a-491c-ad7e-31d833fa4015" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_bae27941-0ed0-4b7c-bbe2-41f93fb0c43f" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_sui_CommonOpUnitsMember_bae27941-0ed0-4b7c-bbe2-41f93fb0c43f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_5740ed31-39a8-460b-8fd8-d9d5990b9db9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_us-gaap_PreferredStockMember_5740ed31-39a8-460b-8fd8-d9d5990b9db9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesIPreferredOPUnitsMember_56bdaf02-9a9e-4b57-8640-28cc5f160315" xlink:href="sui-20210331.xsd#sui_SeriesIPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_sui_SeriesIPreferredOPUnitsMember_56bdaf02-9a9e-4b57-8640-28cc5f160315" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesEPreferredOPUnitsDomain_16223de4-195e-4dea-8032-a7215bf0f9d9" xlink:href="sui-20210331.xsd#sui_SeriesEPreferredOPUnitsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_sui_SeriesEPreferredOPUnitsDomain_16223de4-195e-4dea-8032-a7215bf0f9d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_061716a5-09bb-41ee-ab01-a28abe2448b9" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e6851c3e-5ded-4c19-9553-9c5ed219238f" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_061716a5-09bb-41ee-ab01-a28abe2448b9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_1ee92843-847d-4019-8967-5a30ddfef3a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_1ee92843-847d-4019-8967-5a30ddfef3a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_1ee92843-847d-4019-8967-5a30ddfef3a5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1ee92843-847d-4019-8967-5a30ddfef3a5" xlink:to="loc_us-gaap_EquityComponentDomain_1ee92843-847d-4019-8967-5a30ddfef3a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1ee92843-847d-4019-8967-5a30ddfef3a5" xlink:to="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConversionofCommonOPUnitsMember_cbb098c5-e806-44b5-b33b-8ca26848d0c6" xlink:href="sui-20210331.xsd#sui_ConversionofCommonOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:to="loc_sui_ConversionofCommonOPUnitsMember_cbb098c5-e806-44b5-b33b-8ca26848d0c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA1PreferredOpUnitsMember_ccadbf17-c1db-4fa7-b3ac-50409f7ec543" xlink:href="sui-20210331.xsd#sui_SeriesA1PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:to="loc_sui_SeriesA1PreferredOpUnitsMember_ccadbf17-c1db-4fa7-b3ac-50409f7ec543" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredOpUnitsMember_0ba47d7a-2da6-4d2b-b7ac-80a30c120287" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:to="loc_sui_SeriesA4PreferredOpUnitsMember_0ba47d7a-2da6-4d2b-b7ac-80a30c120287" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_1f8344f7-a650-48ec-87d0-b70f6631ac60" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:to="loc_sui_SeriesA4PreferredStockMember_1f8344f7-a650-48ec-87d0-b70f6631ac60" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesCpreferredOPunitsMember_1b31190a-2761-4215-b58c-a13f2f409532" xlink:href="sui-20210331.xsd#sui_SeriesCpreferredOPunitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_26963d50-f389-4d24-b829-f56775a984ae" xlink:to="loc_sui_SeriesCpreferredOPunitsMember_1b31190a-2761-4215-b58c-a13f2f409532" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_7de26c54-a688-4c8f-b299-b9782052cb32" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_b5ad38d3-4a5c-48de-ae7b-27689e8b4e9d" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_7de26c54-a688-4c8f-b299-b9782052cb32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SHMSouthForkMember_540f2fb3-618e-4d64-b730-c56277e82941" xlink:href="sui-20210331.xsd#sui_SHMSouthForkMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_7de26c54-a688-4c8f-b299-b9782052cb32" xlink:to="loc_sui_SHMSouthForkMember_540f2fb3-618e-4d64-b730-c56277e82941" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_81424f2d-6c7a-4d94-8a13-788497693246" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_81424f2d-6c7a-4d94-8a13-788497693246" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_81424f2d-6c7a-4d94-8a13-788497693246_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_81424f2d-6c7a-4d94-8a13-788497693246" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_81424f2d-6c7a-4d94-8a13-788497693246_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe8c8513-4aba-485b-9d9b-6e743fea1aee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_81424f2d-6c7a-4d94-8a13-788497693246" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe8c8513-4aba-485b-9d9b-6e743fea1aee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SafeHarborMember_c4ac14ed-5dad-4414-907c-dcf8b386a809" xlink:href="sui-20210331.xsd#sui_SafeHarborMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe8c8513-4aba-485b-9d9b-6e743fea1aee" xlink:to="loc_sui_SafeHarborMember_c4ac14ed-5dad-4414-907c-dcf8b386a809" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_39463bbd-15f3-441e-a4b1-7783181e5335" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConversionOfStockTable_d9d651aa-e206-4a80-8749-2afe166d69b6" xlink:to="loc_srt_RangeAxis_39463bbd-15f3-441e-a4b1-7783181e5335" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_39463bbd-15f3-441e-a4b1-7783181e5335_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_39463bbd-15f3-441e-a4b1-7783181e5335" xlink:to="loc_srt_RangeMember_39463bbd-15f3-441e-a4b1-7783181e5335_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b814fad4-9191-4ab7-ba62-6b3d53a4383d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_39463bbd-15f3-441e-a4b1-7783181e5335" xlink:to="loc_srt_RangeMember_b814fad4-9191-4ab7-ba62-6b3d53a4383d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ef2ddd68-af1d-4e48-9dc7-6d07ca80524d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b814fad4-9191-4ab7-ba62-6b3d53a4383d" xlink:to="loc_srt_MinimumMember_ef2ddd68-af1d-4e48-9dc7-6d07ca80524d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1674028c-3089-4dd8-900c-caf975d46893" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b814fad4-9191-4ab7-ba62-6b3d53a4383d" xlink:to="loc_srt_MaximumMember_1674028c-3089-4dd8-900c-caf975d46893" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquityEquityandTemporaryEquityDividendsPayableTableDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquityEquityandTemporaryEquityDividendsPayableTableDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquityEquityandTemporaryEquityDividendsPayableTableDetails" xlink:type="extended" id="id4e1332da0b04c8aa35023fe6f083950_EquityandTemporaryEquityEquityandTemporaryEquityDividendsPayableTableDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsPayableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_15dbba41-7f8a-4e6a-9fd7-34eb077c6945" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_15dbba41-7f8a-4e6a-9fd7-34eb077c6945" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_b476bdea-8b7a-4a27-8fa7-09302328663e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_b476bdea-8b7a-4a27-8fa7-09302328663e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareDeclared_3bbc20ed-6826-4239-994b-16b0b4940ff4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareDeclared_3bbc20ed-6826-4239-994b-16b0b4940ff4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_17dce6db-7488-41a2-bbef-ff1b8b0a9a78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:to="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_17dce6db-7488-41a2-bbef-ff1b8b0a9a78" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsPayableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DividendsPayableLineItems_21f4a249-00ac-47d0-937e-cd46650e6d9e" xlink:to="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_0e287094-dfe6-4bb0-b444-1713447f5f3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_0e287094-dfe6-4bb0-b444-1713447f5f3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0e287094-dfe6-4bb0-b444-1713447f5f3f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_0e287094-dfe6-4bb0-b444-1713447f5f3f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0e287094-dfe6-4bb0-b444-1713447f5f3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e3a2054c-5631-4b14-880b-f50a5aa414cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_0e287094-dfe6-4bb0-b444-1713447f5f3f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e3a2054c-5631-4b14-880b-f50a5aa414cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_4cde1fd0-ddc5-4a17-8849-c92942e5fc0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_e3a2054c-5631-4b14-880b-f50a5aa414cc" xlink:to="loc_us-gaap_SubsequentEventMember_4cde1fd0-ddc5-4a17-8849-c92942e5fc0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:to="loc_srt_StatementScenarioAxis_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_cb784da3-fc79-4806-8925-2db0293bc10f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_0ce8762d-c45b-42d7-98c6-91fc7d00ea9d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_cb784da3-fc79-4806-8925-2db0293bc10f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_1518ebf3-65b6-44c1-a4bf-d9870df01e55" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_cb784da3-fc79-4806-8925-2db0293bc10f" xlink:to="loc_srt_ScenarioForecastMember_1518ebf3-65b6-44c1-a4bf-d9870df01e55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_431fc49a-1d78-436b-b374-e37956734bdf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:to="loc_us-gaap_StatementClassOfStockAxis_431fc49a-1d78-436b-b374-e37956734bdf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_431fc49a-1d78-436b-b374-e37956734bdf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_431fc49a-1d78-436b-b374-e37956734bdf" xlink:to="loc_us-gaap_ClassOfStockDomain_431fc49a-1d78-436b-b374-e37956734bdf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_574f6068-5996-4282-911b-a238841c94cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_431fc49a-1d78-436b-b374-e37956734bdf" xlink:to="loc_us-gaap_ClassOfStockDomain_574f6068-5996-4282-911b-a238841c94cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_bb0805fd-3c90-4083-a423-237cb4f2fc87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_574f6068-5996-4282-911b-a238841c94cd" xlink:to="loc_us-gaap_CommonStockMember_bb0805fd-3c90-4083-a423-237cb4f2fc87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_55cb03c3-c8ef-4d47-b81a-9bdb5aa37afd" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_574f6068-5996-4282-911b-a238841c94cd" xlink:to="loc_sui_SeriesA4PreferredStockMember_55cb03c3-c8ef-4d47-b81a-9bdb5aa37afd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_419a99f8-ad75-4e91-b99f-eb4d6196a697" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DividendsPayableTable_0d38b1d2-bd11-409f-adb7-af554bc891f3" xlink:to="loc_us-gaap_DividendsAxis_419a99f8-ad75-4e91-b99f-eb4d6196a697" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_419a99f8-ad75-4e91-b99f-eb4d6196a697_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_419a99f8-ad75-4e91-b99f-eb4d6196a697" xlink:to="loc_us-gaap_DividendsDomain_419a99f8-ad75-4e91-b99f-eb4d6196a697_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_41de2b98-4634-4385-8cb2-b8779aabfc1e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_419a99f8-ad75-4e91-b99f-eb4d6196a697" xlink:to="loc_us-gaap_DividendsDomain_41de2b98-4634-4385-8cb2-b8779aabfc1e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EquityandTemporaryEquityEquityandTemporaryEquityScheduleofSaleofCommonStockDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EquityandTemporaryEquityEquityandTemporaryEquityScheduleofSaleofCommonStockDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EquityandTemporaryEquityEquityandTemporaryEquityScheduleofSaleofCommonStockDetails" xlink:type="extended" id="i727635024bd04433975b788897a27708_EquityandTemporaryEquityEquityandTemporaryEquityScheduleofSaleofCommonStockDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_61045824-8aea-4f95-8c54-ff28cba2f842" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement_b66c4a3b-4593-4fd2-a5ee-0621c242ddd9" xlink:href="sui-20210331.xsd#sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61045824-8aea-4f95-8c54-ff28cba2f842" xlink:to="loc_sui_AggregateValueofSharestobeIssuedinAccordancetoSalesAgreement_b66c4a3b-4593-4fd2-a5ee-0621c242ddd9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_3c446a55-fc01-47f3-8e7f-6fc8e4c1888d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_61045824-8aea-4f95-8c54-ff28cba2f842" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_3c446a55-fc01-47f3-8e7f-6fc8e4c1888d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_61045824-8aea-4f95-8c54-ff28cba2f842" xlink:to="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_b41d2d81-bb43-41ad-a648-88515c7e6daa" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_srt_StatementScenarioAxis_b41d2d81-bb43-41ad-a648-88515c7e6daa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_b41d2d81-bb43-41ad-a648-88515c7e6daa_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_b41d2d81-bb43-41ad-a648-88515c7e6daa" xlink:to="loc_srt_ScenarioUnspecifiedDomain_b41d2d81-bb43-41ad-a648-88515c7e6daa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_3682e984-7cca-4842-a05f-b4504073e153" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_b41d2d81-bb43-41ad-a648-88515c7e6daa" xlink:to="loc_srt_ScenarioUnspecifiedDomain_3682e984-7cca-4842-a05f-b4504073e153" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f9afe19d-8a50-4cd5-a3cd-75f65346a170" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f9afe19d-8a50-4cd5-a3cd-75f65346a170" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f9afe19d-8a50-4cd5-a3cd-75f65346a170_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f9afe19d-8a50-4cd5-a3cd-75f65346a170" xlink:to="loc_us-gaap_EquityComponentDomain_f9afe19d-8a50-4cd5-a3cd-75f65346a170_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_802fba45-11b3-49ae-9e94-86d8000b96c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f9afe19d-8a50-4cd5-a3cd-75f65346a170" xlink:to="loc_us-gaap_EquityComponentDomain_802fba45-11b3-49ae-9e94-86d8000b96c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7539467d-40d4-44d8-b65c-d48f8b204d3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7539467d-40d4-44d8-b65c-d48f8b204d3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7539467d-40d4-44d8-b65c-d48f8b204d3b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7539467d-40d4-44d8-b65c-d48f8b204d3b" xlink:to="loc_us-gaap_ClassOfStockDomain_7539467d-40d4-44d8-b65c-d48f8b204d3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_969ef517-47d8-49e6-8891-f86ff08a4b2e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7539467d-40d4-44d8-b65c-d48f8b204d3b" xlink:to="loc_us-gaap_ClassOfStockDomain_969ef517-47d8-49e6-8891-f86ff08a4b2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_37624b55-6185-4ab7-bfad-0f9d6762dd2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_37624b55-6185-4ab7-bfad-0f9d6762dd2d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_37624b55-6185-4ab7-bfad-0f9d6762dd2d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_37624b55-6185-4ab7-bfad-0f9d6762dd2d" xlink:to="loc_us-gaap_TypeOfAdoptionMember_37624b55-6185-4ab7-bfad-0f9d6762dd2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_ff572dcf-c277-40a0-9163-37f9ac5dead9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_37624b55-6185-4ab7-bfad-0f9d6762dd2d" xlink:to="loc_us-gaap_TypeOfAdoptionMember_ff572dcf-c277-40a0-9163-37f9ac5dead9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_1fac32ca-5f3d-4d1e-ae07-29ee670fd865" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_1fac32ca-5f3d-4d1e-ae07-29ee670fd865" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_1fac32ca-5f3d-4d1e-ae07-29ee670fd865_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_1fac32ca-5f3d-4d1e-ae07-29ee670fd865" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_1fac32ca-5f3d-4d1e-ae07-29ee670fd865_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_04395f77-4605-48a8-abdb-d1c54accbbfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_1fac32ca-5f3d-4d1e-ae07-29ee670fd865" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_04395f77-4605-48a8-abdb-d1c54accbbfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_6806b60b-aa70-4bda-ba1a-10bc5b065cb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_34587f3e-2a94-4211-9daf-698d68bcac2d" xlink:to="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_6806b60b-aa70-4bda-ba1a-10bc5b065cb4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_6806b60b-aa70-4bda-ba1a-10bc5b065cb4_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForErrorCorrectionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_6806b60b-aa70-4bda-ba1a-10bc5b065cb4" xlink:to="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_6806b60b-aa70-4bda-ba1a-10bc5b065cb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_63d6e254-6521-44c0-b22e-c226de8f9088" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForErrorCorrectionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_6806b60b-aa70-4bda-ba1a-10bc5b065cb4" xlink:to="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_63d6e254-6521-44c0-b22e-c226de8f9088" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ShareBasedCompensation" xlink:type="simple" xlink:href="sui-20210331.xsd#ShareBasedCompensation"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ShareBasedCompensation" xlink:type="extended" id="i690dda43ab204024adcec60001f7656c_ShareBasedCompensation"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ShareBasedCompensationTables" xlink:type="simple" xlink:href="sui-20210331.xsd#ShareBasedCompensationTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ShareBasedCompensationTables" xlink:type="extended" id="i97c99ea9248544939679dd679db9fe76_ShareBasedCompensationTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/ShareBasedCompensationDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#ShareBasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/ShareBasedCompensationDetails" xlink:type="extended" id="i2d46b988481e43e8906cacb351625a57_ShareBasedCompensationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfShareBasedCompensationPlans_ba8be90f-f7a0-4c91-b128-42f015e6d151" xlink:href="sui-20210331.xsd#sui_NumberOfShareBasedCompensationPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_sui_NumberOfShareBasedCompensationPlans_ba8be90f-f7a0-4c91-b128-42f015e6d151" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPercentExpectedToVest_7431281d-c4b2-47f8-9665-a3c2eb19f795" xlink:href="sui-20210331.xsd#sui_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPercentExpectedToVest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_sui_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPercentExpectedToVest_7431281d-c4b2-47f8-9665-a3c2eb19f795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_79aa4990-5f21-46a3-b0e1-a1b46a60f2ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_SharePrice_79aa4990-5f21-46a3-b0e1-a1b46a60f2ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_3bf4a4ee-ab7e-4f22-afaf-de160c15b74c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_3bf4a4ee-ab7e-4f22-afaf-de160c15b74c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2e4b287e-3b6e-459e-8c05-9d7123183bec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2e4b287e-3b6e-459e-8c05-9d7123183bec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_e757e793-cdff-4652-afc0-699bb9f7c125" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_e757e793-cdff-4652-afc0-699bb9f7c125" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7991ac59-c59e-452c-b398-3672d1a1ad32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7991ac59-c59e-452c-b398-3672d1a1ad32" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_4897c04e-4e44-431a-bf97-fe849f06783b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_4897c04e-4e44-431a-bf97-fe849f06783b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_fcd41825-df8d-4bd9-8143-aefce125e2da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_fcd41825-df8d-4bd9-8143-aefce125e2da" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_be599fc5-9fc1-4b2e-8db0-098c25f11445" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_be599fc5-9fc1-4b2e-8db0-098c25f11445" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_6626e76b-aaf5-454e-8dbf-4927d775e4f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_6626e76b-aaf5-454e-8dbf-4927d775e4f4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_8d11a176-a72b-434b-b3e3-43ea0b9c0a01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_8d11a176-a72b-434b-b3e3-43ea0b9c0a01" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5040cbbc-384e-43a5-bb24-4ec8f5be6ee3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_27034467-7086-4221-a200-5a5eb0a52e9b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_us-gaap_AwardDateAxis_27034467-7086-4221-a200-5a5eb0a52e9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_27034467-7086-4221-a200-5a5eb0a52e9b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_27034467-7086-4221-a200-5a5eb0a52e9b" xlink:to="loc_us-gaap_AwardDateDomain_27034467-7086-4221-a200-5a5eb0a52e9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_27034467-7086-4221-a200-5a5eb0a52e9b" xlink:to="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateOneMember_b4b282f2-268e-4449-bab2-75146ddbeb40" xlink:href="sui-20210331.xsd#sui_AwardDateOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateOneMember_b4b282f2-268e-4449-bab2-75146ddbeb40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateTwoMember_72858fc4-5b8d-4416-8117-b4793078661c" xlink:href="sui-20210331.xsd#sui_AwardDateTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateTwoMember_72858fc4-5b8d-4416-8117-b4793078661c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateThreeMember_511e66e7-4526-4508-bd1e-56ad29db686b" xlink:href="sui-20210331.xsd#sui_AwardDateThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateThreeMember_511e66e7-4526-4508-bd1e-56ad29db686b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateFourMember_7bcae8b2-69ed-4988-bc5b-c03237590175" xlink:href="sui-20210331.xsd#sui_AwardDateFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateFourMember_7bcae8b2-69ed-4988-bc5b-c03237590175" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateFiveMember_adfdc1dd-1a2b-4316-9517-8cd7a37b8c84" xlink:href="sui-20210331.xsd#sui_AwardDateFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateFiveMember_adfdc1dd-1a2b-4316-9517-8cd7a37b8c84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AwardDateSixMember_01d8598b-0b5b-4a12-a569-1bf3c813ce60" xlink:href="sui-20210331.xsd#sui_AwardDateSixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_42b0f311-1bf4-4be3-95fe-898cac874177" xlink:to="loc_sui_AwardDateSixMember_01d8598b-0b5b-4a12-a569-1bf3c813ce60" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_cac6a8d9-c45d-4a14-972a-3e03004bd0db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_cac6a8d9-c45d-4a14-972a-3e03004bd0db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_cac6a8d9-c45d-4a14-972a-3e03004bd0db_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cac6a8d9-c45d-4a14-972a-3e03004bd0db" xlink:to="loc_us-gaap_EquityComponentDomain_cac6a8d9-c45d-4a14-972a-3e03004bd0db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_ae73b7c7-3e13-4fa6-936f-e6e96fb095ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cac6a8d9-c45d-4a14-972a-3e03004bd0db" xlink:to="loc_us-gaap_EquityComponentDomain_ae73b7c7-3e13-4fa6-936f-e6e96fb095ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_dd7fd5ad-fdff-4b39-b505-a6d4a349c17e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ae73b7c7-3e13-4fa6-936f-e6e96fb095ab" xlink:to="loc_us-gaap_CommonStockMember_dd7fd5ad-fdff-4b39-b505-a6d4a349c17e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VestingTypeAxis_b4a78219-7de1-4623-a932-2e3828cb2c94" xlink:href="sui-20210331.xsd#sui_VestingTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_sui_VestingTypeAxis_b4a78219-7de1-4623-a932-2e3828cb2c94" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VestingTypeDomain_b4a78219-7de1-4623-a932-2e3828cb2c94_default" xlink:href="sui-20210331.xsd#sui_VestingTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_VestingTypeAxis_b4a78219-7de1-4623-a932-2e3828cb2c94" xlink:to="loc_sui_VestingTypeDomain_b4a78219-7de1-4623-a932-2e3828cb2c94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_VestingTypeDomain_99dcd18e-0404-4d1e-8e34-48db4b8f9cda" xlink:href="sui-20210331.xsd#sui_VestingTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_VestingTypeAxis_b4a78219-7de1-4623-a932-2e3828cb2c94" xlink:to="loc_sui_VestingTypeDomain_99dcd18e-0404-4d1e-8e34-48db4b8f9cda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TimeBasedMember_ca9da85f-cf0b-46b6-9203-b8cc8b66db59" xlink:href="sui-20210331.xsd#sui_TimeBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_VestingTypeDomain_99dcd18e-0404-4d1e-8e34-48db4b8f9cda" xlink:to="loc_sui_TimeBasedMember_ca9da85f-cf0b-46b6-9203-b8cc8b66db59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarketConditionMember_05efe253-0d7d-4e49-bcb5-e9deef314f18" xlink:href="sui-20210331.xsd#sui_MarketConditionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_sui_VestingTypeDomain_99dcd18e-0404-4d1e-8e34-48db4b8f9cda" xlink:to="loc_sui_MarketConditionMember_05efe253-0d7d-4e49-bcb5-e9deef314f18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_4a22f608-a88f-418e-8cbe-976d0ec158f6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_srt_TitleOfIndividualAxis_4a22f608-a88f-418e-8cbe-976d0ec158f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_4a22f608-a88f-418e-8cbe-976d0ec158f6_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_4a22f608-a88f-418e-8cbe-976d0ec158f6" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_4a22f608-a88f-418e-8cbe-976d0ec158f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ecf6b984-79c1-4bab-b91d-a2da20f3873b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_4a22f608-a88f-418e-8cbe-976d0ec158f6" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ecf6b984-79c1-4bab-b91d-a2da20f3873b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ExecutiveOfficerMember_fcb0b7e0-2f68-443a-8a78-fca3081cfb2d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ecf6b984-79c1-4bab-b91d-a2da20f3873b" xlink:to="loc_srt_ExecutiveOfficerMember_fcb0b7e0-2f68-443a-8a78-fca3081cfb2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_86761543-ff4f-4d88-81df-b79b3c4a648b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ecf6b984-79c1-4bab-b91d-a2da20f3873b" xlink:to="loc_srt_DirectorMember_86761543-ff4f-4d88-81df-b79b3c4a648b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_KeyEmployeesMember_0a852a4d-cc66-4a03-8103-5fc2e6420293" xlink:href="sui-20210331.xsd#sui_KeyEmployeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_ecf6b984-79c1-4bab-b91d-a2da20f3873b" xlink:to="loc_sui_KeyEmployeesMember_0a852a4d-cc66-4a03-8103-5fc2e6420293" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_4fdb8d88-96ff-4458-8327-eeabe642603b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_us-gaap_AwardTypeAxis_4fdb8d88-96ff-4458-8327-eeabe642603b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4fdb8d88-96ff-4458-8327-eeabe642603b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4fdb8d88-96ff-4458-8327-eeabe642603b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4fdb8d88-96ff-4458-8327-eeabe642603b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1ada1574-8f84-4ca3-81a4-64e0fde7d745" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4fdb8d88-96ff-4458-8327-eeabe642603b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1ada1574-8f84-4ca3-81a4-64e0fde7d745" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_4fc184ef-44b5-485a-af16-9788e99e1008" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1ada1574-8f84-4ca3-81a4-64e0fde7d745" xlink:to="loc_us-gaap_RestrictedStockMember_4fc184ef-44b5-485a-af16-9788e99e1008" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_0e243ce8-8da5-496d-b7cd-deb78a29af43" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1ada1574-8f84-4ca3-81a4-64e0fde7d745" xlink:to="loc_us-gaap_EmployeeStockOptionMember_0e243ce8-8da5-496d-b7cd-deb78a29af43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_134beb47-d665-4720-9ffd-b0d193b25dad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b28cd8ce-2518-4935-a3a2-47ba50958242" xlink:to="loc_us-gaap_PlanNameAxis_134beb47-d665-4720-9ffd-b0d193b25dad" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_134beb47-d665-4720-9ffd-b0d193b25dad_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_134beb47-d665-4720-9ffd-b0d193b25dad" xlink:to="loc_us-gaap_PlanNameDomain_134beb47-d665-4720-9ffd-b0d193b25dad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_155cfc65-3252-4843-9c57-c177b079b5b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_134beb47-d665-4720-9ffd-b0d193b25dad" xlink:to="loc_us-gaap_PlanNameDomain_155cfc65-3252-4843-9c57-c177b079b5b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TwoThousandFifteenEquityPlanMember_f167fd0b-f467-4c68-a6fd-853f1c21fd10" xlink:href="sui-20210331.xsd#sui_TwoThousandFifteenEquityPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_155cfc65-3252-4843-9c57-c177b079b5b2" xlink:to="loc_sui_TwoThousandFifteenEquityPlanMember_f167fd0b-f467-4c68-a6fd-853f1c21fd10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_A2004NonemployeePlanMember_0fce8357-ab12-4ce1-b339-aed1ab052d82" xlink:href="sui-20210331.xsd#sui_A2004NonemployeePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_155cfc65-3252-4843-9c57-c177b079b5b2" xlink:to="loc_sui_A2004NonemployeePlanMember_0fce8357-ab12-4ce1-b339-aed1ab052d82" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SegmentReporting" xlink:type="simple" xlink:href="sui-20210331.xsd#SegmentReporting"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SegmentReporting" xlink:type="extended" id="ic42df721502e4900a8a7e7dc47e45b9b_SegmentReporting"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SegmentReportingTables" xlink:type="simple" xlink:href="sui-20210331.xsd#SegmentReportingTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SegmentReportingTables" xlink:type="extended" id="ib11dfade91534f1e9d984ef8c333295a_SegmentReportingTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SegmentReportingSegmentReportingSeasonalityDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#SegmentReportingSegmentReportingSeasonalityDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SegmentReportingSegmentReportingSeasonalityDetails" xlink:type="extended" id="ie79311c01fad45e8b25015d2d9fed454_SegmentReportingSegmentReportingSeasonalityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_630655d5-bd84-4da4-96ea-befc4753a64d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_us-gaap_NumberOfReportableSegments_630655d5-bd84-4da4-96ea-befc4753a64d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TransientRVRevenue_fdf5d7f2-1e77-43e3-8217-5f7c3a429697" xlink:href="sui-20210331.xsd#sui_TransientRVRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_sui_TransientRVRevenue_fdf5d7f2-1e77-43e3-8217-5f7c3a429697" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TransientRVRentalRevenueRecognizedPercentage_096ae90e-e984-4a31-b453-38343a7907de" xlink:href="sui-20210331.xsd#sui_TransientRVRentalRevenueRecognizedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_sui_TransientRVRentalRevenueRecognizedPercentage_096ae90e-e984-4a31-b453-38343a7907de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_34bea38d-4f5c-4950-beb9-5a0baa95849d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_us-gaap_Assets_34bea38d-4f5c-4950-beb9-5a0baa95849d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_d22b3959-c311-43ee-bd4b-e13f1604f494" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_us-gaap_Goodwill_d22b3959-c311-43ee-bd4b-e13f1604f494" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_5845b891-4e11-4c4e-80f3-498199d340dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_742726df-0057-45ef-bbbf-4d9840c57561" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_5845b891-4e11-4c4e-80f3-498199d340dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_b4e790f9-d69a-4921-8e0d-dcb6f26778d7" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_5845b891-4e11-4c4e-80f3-498199d340dd" xlink:to="loc_srt_StatementScenarioAxis_b4e790f9-d69a-4921-8e0d-dcb6f26778d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_b4e790f9-d69a-4921-8e0d-dcb6f26778d7_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_b4e790f9-d69a-4921-8e0d-dcb6f26778d7" xlink:to="loc_srt_ScenarioUnspecifiedDomain_b4e790f9-d69a-4921-8e0d-dcb6f26778d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_cac99846-bdcc-41cc-b524-00f5dc2442a6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_b4e790f9-d69a-4921-8e0d-dcb6f26778d7" xlink:to="loc_srt_ScenarioUnspecifiedDomain_cac99846-bdcc-41cc-b524-00f5dc2442a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_42fcefc6-05f3-4fd2-88e6-ddc9deed691a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_cac99846-bdcc-41cc-b524-00f5dc2442a6" xlink:to="loc_srt_ScenarioForecastMember_42fcefc6-05f3-4fd2-88e6-ddc9deed691a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_2f020b61-60e2-4bb9-8852-6c1523532c53" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_5845b891-4e11-4c4e-80f3-498199d340dd" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_2f020b61-60e2-4bb9-8852-6c1523532c53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_2f020b61-60e2-4bb9-8852-6c1523532c53_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2f020b61-60e2-4bb9-8852-6c1523532c53" xlink:to="loc_us-gaap_SegmentDomain_2f020b61-60e2-4bb9-8852-6c1523532c53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_648a6612-b473-4646-8a2a-9182fbfa14eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2f020b61-60e2-4bb9-8852-6c1523532c53" xlink:to="loc_us-gaap_SegmentDomain_648a6612-b473-4646-8a2a-9182fbfa14eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RealPropertyOperationsSegmentMember_ad0aeadc-4454-4287-b1c4-3cb0aed867d8" xlink:href="sui-20210331.xsd#sui_RealPropertyOperationsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_648a6612-b473-4646-8a2a-9182fbfa14eb" xlink:to="loc_sui_RealPropertyOperationsSegmentMember_ad0aeadc-4454-4287-b1c4-3cb0aed867d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarinaSaleSegmentMember_a3c4187f-8754-4b60-845f-1bd1ed22daee" xlink:href="sui-20210331.xsd#sui_MarinaSaleSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_648a6612-b473-4646-8a2a-9182fbfa14eb" xlink:to="loc_sui_MarinaSaleSegmentMember_a3c4187f-8754-4b60-845f-1bd1ed22daee" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SegmentReportingResultsofOperationsDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#SegmentReportingResultsofOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SegmentReportingResultsofOperationsDetails" xlink:type="extended" id="i063981d0fb5e4d3ca3296e1961dca372_SegmentReportingResultsofOperationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_6e4a277f-7c31-4afd-a036-0fd3d28b61b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_Revenues_6e4a277f-7c31-4afd-a036-0fd3d28b61b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OperatingExpensesAndCostOfSales_f4453f25-33e3-4543-bbd8-cdd8c8975fd6" xlink:href="sui-20210331.xsd#sui_OperatingExpensesAndCostOfSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_OperatingExpensesAndCostOfSales_f4453f25-33e3-4543-bbd8-cdd8c8975fd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_34b70b4a-cdc9-4c51-a5ab-9f388dc344d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_OperatingIncomeLoss_34b70b4a-cdc9-4c51-a5ab-9f388dc344d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherRevenuesSegment_2a9023ff-9f27-451b-a30c-d5277f37f77e" xlink:href="sui-20210331.xsd#sui_OtherRevenuesSegment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_OtherRevenuesSegment_2a9023ff-9f27-451b-a30c-d5277f37f77e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_Brokeragecommissionsandotherincomenet_fb8ecc5f-c63e-4467-8c2e-3e953340b4b4" xlink:href="sui-20210331.xsd#sui_Brokeragecommissionsandotherincomenet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_Brokeragecommissionsandotherincomenet_fb8ecc5f-c63e-4467-8c2e-3e953340b4b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingExpense_95d9d09b-b116-4ac3-863c-b5d68e85010a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_SellingExpense_95d9d09b-b116-4ac3-863c-b5d68e85010a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_ac9289c4-6a04-4202-8a49-c3f16a508a3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_ac9289c4-6a04-4202-8a49-c3f16a508a3d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossFromCatastrophes_58a171c3-4e49-4085-84af-a9ffb39a5d6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossFromCatastrophes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_LossFromCatastrophes_58a171c3-4e49-4085-84af-a9ffb39a5d6f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized_2a06d5f3-03be-4c71-8ccf-2295b8f57a61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized_2a06d5f3-03be-4c71-8ccf-2295b8f57a61" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_3803f164-af18-4cb9-8896-ce9e936ff14e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_DepreciationAndAmortization_3803f164-af18-4cb9-8896-ce9e936ff14e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_4dc9b6b9-d7a0-43b7-a4ec-54f1c969bdb9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_4dc9b6b9-d7a0-43b7-a4ec-54f1c969bdb9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_00604c9d-e032-4353-8c8d-be878bc90bfa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_InterestExpense_00604c9d-e032-4353-8c8d-be878bc90bfa" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOther_59f49369-a375-4be6-8855-3a111609c3fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_InterestExpenseOther_59f49369-a375-4be6-8855-3a111609c3fe" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RemeasurementOfMarketableSecurities_d557f667-b242-476b-b6db-73392a7f409b" xlink:href="sui-20210331.xsd#sui_RemeasurementOfMarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_RemeasurementOfMarketableSecurities_d557f667-b242-476b-b6db-73392a7f409b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_bb970563-b6a3-443b-bdf5-de82e2703c29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_bb970563-b6a3-443b-bdf5-de82e2703c29" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfProperties_ff0159eb-4ff4-4bb6-aa26-62b36eec7478" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_GainLossOnSaleOfProperties_ff0159eb-4ff4-4bb6-aa26-62b36eec7478" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_23f8e704-bdb7-4f67-ae65-cd6a5f2768ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_23f8e704-bdb7-4f67-ae65-cd6a5f2768ca" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LossonRemeasurementofNotesReceivable_21314548-4447-40fc-b2aa-9a06c2281087" xlink:href="sui-20210331.xsd#sui_LossonRemeasurementofNotesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_LossonRemeasurementofNotesReceivable_21314548-4447-40fc-b2aa-9a06c2281087" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DistributionsFromAffiliate_402fcd25-98a2-4bb9-ab3f-f0d432fe998f" xlink:href="sui-20210331.xsd#sui_DistributionsFromAffiliate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_DistributionsFromAffiliate_402fcd25-98a2-4bb9-ab3f-f0d432fe998f" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LossonRemeasurementofInvestment_d5a42c61-8252-4bad-8464-0ac0565d8741" xlink:href="sui-20210331.xsd#sui_LossonRemeasurementofInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_LossonRemeasurementofInvestment_d5a42c61-8252-4bad-8464-0ac0565d8741" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_5e6a01b4-de29-4d4b-8199-b45c0f15c94a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_5e6a01b4-de29-4d4b-8199-b45c0f15c94a" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_2d5cc407-403c-4a6c-9c4c-64f8c60a26fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_2d5cc407-403c-4a6c-9c4c-64f8c60a26fd" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_8ba0dd22-caf8-46eb-98b6-c48b84aabca1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_ProfitLoss_8ba0dd22-caf8-46eb-98b6-c48b84aabca1" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PreferredreturntoSeriesA1preferredOPunits_24f9d9a4-7794-4ad5-98f9-9ff25ce78eb4" xlink:href="sui-20210331.xsd#sui_PreferredreturntoSeriesA1preferredOPunits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_sui_PreferredreturntoSeriesA1preferredOPunits_24f9d9a4-7794-4ad5-98f9-9ff25ce78eb4" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable_8d37f18c-24f3-4615-a086-cd3bb92220b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable_8d37f18c-24f3-4615-a086-cd3bb92220b9" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_2afb5706-d9f4-4c08-8cd1-4f660b6a33fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_2afb5706-d9f4-4c08-8cd1-4f660b6a33fc" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_ed97a194-a679-43c6-9918-11a01fa4b902" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_ed97a194-a679-43c6-9918-11a01fa4b902" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_da5707da-92fb-4b62-a2bd-fe865d69bb02" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_af65fb90-837a-4873-8a76-cc6f142abe59" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_da5707da-92fb-4b62-a2bd-fe865d69bb02" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_da5707da-92fb-4b62-a2bd-fe865d69bb02" xlink:to="loc_srt_ConsolidationItemsAxis_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4" xlink:to="loc_srt_ConsolidationItemsDomain_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_0b3c2166-8f86-4a33-b90d-8d87ef155577" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_8277aaa1-87bb-4467-a0c5-cf2a9e2d6db4" xlink:to="loc_srt_ConsolidationItemsDomain_0b3c2166-8f86-4a33-b90d-8d87ef155577" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_b0cf92c2-7447-4057-ab3f-d9c9f9da12d2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0b3c2166-8f86-4a33-b90d-8d87ef155577" xlink:to="loc_us-gaap_OperatingSegmentsMember_b0cf92c2-7447-4057-ab3f-d9c9f9da12d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_2171dd77-97e8-4498-a098-ad3e9c99a2cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0b3c2166-8f86-4a33-b90d-8d87ef155577" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_2171dd77-97e8-4498-a098-ad3e9c99a2cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_9a5a30d3-88a1-468f-9630-e60fa41860cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_da5707da-92fb-4b62-a2bd-fe865d69bb02" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_9a5a30d3-88a1-468f-9630-e60fa41860cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9a5a30d3-88a1-468f-9630-e60fa41860cc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9a5a30d3-88a1-468f-9630-e60fa41860cc" xlink:to="loc_us-gaap_SegmentDomain_9a5a30d3-88a1-468f-9630-e60fa41860cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9a5a30d3-88a1-468f-9630-e60fa41860cc" xlink:to="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RealPropertyOperationsSegmentMember_e9d54f85-37f8-48f9-aa6d-9a4cbff0d29d" xlink:href="sui-20210331.xsd#sui_RealPropertyOperationsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:to="loc_sui_RealPropertyOperationsSegmentMember_e9d54f85-37f8-48f9-aa6d-9a4cbff0d29d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HomeSalesAndHomeRentalsSegmentMember_2183bf9c-6dab-4c02-822c-1c8d772ef5fe" xlink:href="sui-20210331.xsd#sui_HomeSalesAndHomeRentalsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:to="loc_sui_HomeSalesAndHomeRentalsSegmentMember_2183bf9c-6dab-4c02-822c-1c8d772ef5fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RVMember_eda8e40a-3987-4296-b853-6181d8f732b7" xlink:href="sui-20210331.xsd#sui_RVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:to="loc_sui_RVMember_eda8e40a-3987-4296-b853-6181d8f732b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MHMember_c3252299-60fc-4c44-8c52-b964cab8eec0" xlink:href="sui-20210331.xsd#sui_MHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:to="loc_sui_MHMember_c3252299-60fc-4c44-8c52-b964cab8eec0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarinasMember_9798a1ec-0318-476b-8527-785f33077f2b" xlink:href="sui-20210331.xsd#sui_MarinasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1fe824ed-9b23-4346-bb22-fe34a55828ae" xlink:to="loc_sui_MarinasMember_9798a1ec-0318-476b-8527-785f33077f2b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SegmentReportingIdentifiableAssetsDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#SegmentReportingIdentifiableAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SegmentReportingIdentifiableAssetsDetails" xlink:type="extended" id="i11b66ecdf8a543d7b562c5a6a924a9f6_SegmentReportingIdentifiableAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateInvestmentPropertyNet_628ac961-850f-4c39-bf7c-93cc59354a82" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RealEstateInvestmentPropertyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_RealEstateInvestmentPropertyNet_628ac961-850f-4c39-bf7c-93cc59354a82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3775ae06-36f4-45ff-9573-5d3b25ebe4aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3775ae06-36f4-45ff-9573-5d3b25ebe4aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_492d96b9-46c2-41e0-9227-5685d1a034e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_492d96b9-46c2-41e0-9227-5685d1a034e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecurities_cfdf06f1-8c52-48df-8590-7c8e6e3699b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_MarketableSecurities_cfdf06f1-8c52-48df-8590-7c8e6e3699b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedHomes_6cb4d9db-ae7b-44d4-9fe6-ebe787578461" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryFinishedHomes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_InventoryFinishedHomes_6cb4d9db-ae7b-44d4-9fe6-ebe787578461" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsAndNotesReceivableNet_7ae12541-5220-4678-ab2c-d07c925a476f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsAndNotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_AccountsAndNotesReceivableNet_7ae12541-5220-4678-ab2c-d07c925a476f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_07d98b5c-2a70-4bf7-9117-240bad1f634a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_Goodwill_07d98b5c-2a70-4bf7-9117-240bad1f634a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_88e50dca-a751-4710-a85c-34f0519e9f04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_88e50dca-a751-4710-a85c-34f0519e9f04" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_e0d05d46-c57c-45ec-a661-a4df6fd7492a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_OtherAssets_e0d05d46-c57c-45ec-a661-a4df6fd7492a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_28778b57-4750-434f-8621-1bd66ca5cc37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_Assets_28778b57-4750-434f-8621-1bd66ca5cc37" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_81c74550-ea24-4271-8865-94ec344f1b93" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_e6d7de87-0fd9-44d7-b211-44fb61cb8220" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_81c74550-ea24-4271-8865-94ec344f1b93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_559f0df1-91b8-480e-a261-d8d9357c1d5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_81c74550-ea24-4271-8865-94ec344f1b93" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_559f0df1-91b8-480e-a261-d8d9357c1d5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_559f0df1-91b8-480e-a261-d8d9357c1d5c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_559f0df1-91b8-480e-a261-d8d9357c1d5c" xlink:to="loc_us-gaap_SegmentDomain_559f0df1-91b8-480e-a261-d8d9357c1d5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c73949ac-0df9-48cd-806e-564217404613" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_559f0df1-91b8-480e-a261-d8d9357c1d5c" xlink:to="loc_us-gaap_SegmentDomain_c73949ac-0df9-48cd-806e-564217404613" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RealPropertyOperationsSegmentMember_8219a6e1-1a03-4e44-8182-128cb5764066" xlink:href="sui-20210331.xsd#sui_RealPropertyOperationsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c73949ac-0df9-48cd-806e-564217404613" xlink:to="loc_sui_RealPropertyOperationsSegmentMember_8219a6e1-1a03-4e44-8182-128cb5764066" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HomeSalesAndHomeRentalsSegmentMember_f5b72e37-5886-4ba0-87b1-d99ba188e43e" xlink:href="sui-20210331.xsd#sui_HomeSalesAndHomeRentalsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c73949ac-0df9-48cd-806e-564217404613" xlink:to="loc_sui_HomeSalesAndHomeRentalsSegmentMember_f5b72e37-5886-4ba0-87b1-d99ba188e43e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarinaSaleSegmentMember_098729df-40dd-481f-b722-f8a4b765b993" xlink:href="sui-20210331.xsd#sui_MarinaSaleSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c73949ac-0df9-48cd-806e-564217404613" xlink:to="loc_sui_MarinaSaleSegmentMember_098729df-40dd-481f-b722-f8a4b765b993" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IncomeTaxes" xlink:type="simple" xlink:href="sui-20210331.xsd#IncomeTaxes"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IncomeTaxes" xlink:type="extended" id="ibf3145d1166a4cc285d1eecff5733af7_IncomeTaxes"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended" id="i5dd91f8e241b46238de8b304cae6e87c_IncomeTaxesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MinimumPercentOfIncomeFromQualifyingSourcesToAllowForRealEstateInvestmentTrustClassification_6ea0fb83-2f06-492f-8e82-e68b455dbd9c" xlink:href="sui-20210331.xsd#sui_MinimumPercentOfIncomeFromQualifyingSourcesToAllowForRealEstateInvestmentTrustClassification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_sui_MinimumPercentOfIncomeFromQualifyingSourcesToAllowForRealEstateInvestmentTrustClassification_6ea0fb83-2f06-492f-8e82-e68b455dbd9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RequiredMinimumPercentOfTaxableIncomeDistributedToStockHolders_ad1b56e7-e57f-433c-8233-58b1645c0849" xlink:href="sui-20210331.xsd#sui_RequiredMinimumPercentOfTaxableIncomeDistributedToStockHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_sui_RequiredMinimumPercentOfTaxableIncomeDistributedToStockHolders_ad1b56e7-e57f-433c-8233-58b1645c0849" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_71efc485-5c1b-4771-82fa-74d990f1b377" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_71efc485-5c1b-4771-82fa-74d990f1b377" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_dafc2068-9364-470c-bc89-c1b71ae174ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_dafc2068-9364-470c-bc89-c1b71ae174ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_ab6a27b5-bfe1-4375-8393-ad6b710cd3df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_ab6a27b5-bfe1-4375-8393-ad6b710cd3df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_81f47087-f7c0-4aaf-a7d5-2c8732cfc288" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_81f47087-f7c0-4aaf-a7d5-2c8732cfc288" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_bd5d9151-095c-48c7-a453-d071c91578b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_00e608ce-6ee3-4eff-bda1-5775a4897814" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_bd5d9151-095c-48c7-a453-d071c91578b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_dee5b4d2-b3c9-4c73-8152-a9a91f24d488" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_bd5d9151-095c-48c7-a453-d071c91578b4" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_dee5b4d2-b3c9-4c73-8152-a9a91f24d488" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_dee5b4d2-b3c9-4c73-8152-a9a91f24d488_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_dee5b4d2-b3c9-4c73-8152-a9a91f24d488" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_dee5b4d2-b3c9-4c73-8152-a9a91f24d488_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_459cfafb-4ec6-4290-8bd6-327dd232b4c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_dee5b4d2-b3c9-4c73-8152-a9a91f24d488" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_459cfafb-4ec6-4290-8bd6-327dd232b4c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_45e0186f-1621-44aa-8be7-e8eb9c977725" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_459cfafb-4ec6-4290-8bd6-327dd232b4c9" xlink:to="loc_us-gaap_ForeignCountryMember_45e0186f-1621-44aa-8be7-e8eb9c977725" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_64c4a26e-a4d7-4779-aa09-2218de30ed13" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_459cfafb-4ec6-4290-8bd6-327dd232b4c9" xlink:to="loc_us-gaap_DomesticCountryMember_64c4a26e-a4d7-4779-aa09-2218de30ed13" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EarningsPerShare" xlink:type="simple" xlink:href="sui-20210331.xsd#EarningsPerShare"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EarningsPerShare" xlink:type="extended" id="i26c179e55a994dfea29c596907cb1418_EarningsPerShare"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EarningsPerShareTables" xlink:type="simple" xlink:href="sui-20210331.xsd#EarningsPerShareTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EarningsPerShareTables" xlink:type="extended" id="i2e3c6c4a0ce44048b4b7362e078a525d_EarningsPerShareTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EarningsPerShareCalculationofNumeratorandDenominatorDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EarningsPerShareCalculationofNumeratorandDenominatorDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EarningsPerShareCalculationofNumeratorandDenominatorDetails" xlink:type="extended" id="ie8cf7312f32b49a58b0cf22de97136fe_EarningsPerShareCalculationofNumeratorandDenominatorDetails"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/EarningsPerShareAntidilutiveSecuritiesExcludedfromComputationofLossPerShareDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#EarningsPerShareAntidilutiveSecuritiesExcludedfromComputationofLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/EarningsPerShareAntidilutiveSecuritiesExcludedfromComputationofLossPerShareDetails" xlink:type="extended" id="i48ec7eb0142a41bdab2d842ea2bd10bc_EarningsPerShareAntidilutiveSecuritiesExcludedfromComputationofLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_127c09e6-925c-44d9-9435-4e89e8e43d5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1777cad5-9e08-45fc-a145-6e1226cc4adb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_127c09e6-925c-44d9-9435-4e89e8e43d5a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1777cad5-9e08-45fc-a145-6e1226cc4adb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1d49265a-cdfc-4a4e-8b08-a746c325b1d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_127c09e6-925c-44d9-9435-4e89e8e43d5a" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1d49265a-cdfc-4a4e-8b08-a746c325b1d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1d49265a-cdfc-4a4e-8b08-a746c325b1d3" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6037eaf9-0b6a-4af0-9cde-1835fb2c7bc3" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CommonOpUnitsMember_eb0918c3-b728-48c1-9859-93e0583cf67b" xlink:href="sui-20210331.xsd#sui_CommonOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_CommonOpUnitsMember_eb0918c3-b728-48c1-9859-93e0583cf67b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA1PreferredOpUnitsMember_d168f65d-5020-4440-8282-69f6dc951ec2" xlink:href="sui-20210331.xsd#sui_SeriesA1PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesA1PreferredOpUnitsMember_d168f65d-5020-4440-8282-69f6dc951ec2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesDPreferredOPUnitsMember_4a4630eb-c234-474c-8d44-f387981eef7a" xlink:href="sui-20210331.xsd#sui_SeriesDPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesDPreferredOPUnitsMember_4a4630eb-c234-474c-8d44-f387981eef7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA3PreferredOpUnitsMember_fa7ed19d-c54d-4542-8f79-2f54fe9654d9" xlink:href="sui-20210331.xsd#sui_SeriesA3PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesA3PreferredOpUnitsMember_fa7ed19d-c54d-4542-8f79-2f54fe9654d9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredOpUnitsMember_5232a502-008d-4297-9d9b-09dfa2661fe0" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesA4PreferredOpUnitsMember_5232a502-008d-4297-9d9b-09dfa2661fe0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesA4PreferredStockMember_3d01f6fe-059f-4b4d-a35c-03e97089d591" xlink:href="sui-20210331.xsd#sui_SeriesA4PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesA4PreferredStockMember_3d01f6fe-059f-4b4d-a35c-03e97089d591" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesCpreferredOPunitsMember_07578f1a-8c9d-4869-bb19-c0ac0018e709" xlink:href="sui-20210331.xsd#sui_SeriesCpreferredOPunitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesCpreferredOPunitsMember_07578f1a-8c9d-4869-bb19-c0ac0018e709" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AspenPreferredOpUnitsMember_f8d8bb57-94ef-4994-bd51-105f1569b066" xlink:href="sui-20210331.xsd#sui_AspenPreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_AspenPreferredOpUnitsMember_f8d8bb57-94ef-4994-bd51-105f1569b066" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesEPreferredOPUnitsMember_85821b81-bfcf-432b-b668-8c220e216466" xlink:href="sui-20210331.xsd#sui_SeriesEPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesEPreferredOPUnitsMember_85821b81-bfcf-432b-b668-8c220e216466" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesFPreferredOPUnitsMember_052f1756-7ed6-4f5e-b8e5-60737a36c1fa" xlink:href="sui-20210331.xsd#sui_SeriesFPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesFPreferredOPUnitsMember_052f1756-7ed6-4f5e-b8e5-60737a36c1fa" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesGPreferredOPUnitsMember_e66ae5a8-3e5b-4441-ba49-1435c79a43ee" xlink:href="sui-20210331.xsd#sui_SeriesGPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesGPreferredOPUnitsMember_e66ae5a8-3e5b-4441-ba49-1435c79a43ee" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesHPreferredOPUnitsMember_8f03cefb-a9ca-4f75-8bcc-16270606adc6" xlink:href="sui-20210331.xsd#sui_SeriesHPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesHPreferredOPUnitsMember_8f03cefb-a9ca-4f75-8bcc-16270606adc6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesIPreferredOPUnitsMember_66cfec85-c3d0-4847-a61e-9ad7975a219c" xlink:href="sui-20210331.xsd#sui_SeriesIPreferredOPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_a95fd741-26ac-426f-994e-a526413e02e1" xlink:to="loc_sui_SeriesIPreferredOPUnitsMember_66cfec85-c3d0-4847-a61e-9ad7975a219c" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/FairValueofFinancialInstruments" xlink:type="simple" xlink:href="sui-20210331.xsd#FairValueofFinancialInstruments"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/FairValueofFinancialInstruments" xlink:type="extended" id="i1399ce7f3de644bdb8ed00f584ffe77c_FairValueofFinancialInstruments"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsTables" xlink:type="simple" xlink:href="sui-20210331.xsd#FairValueofFinancialInstrumentsTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsTables" xlink:type="extended" id="i20436a384ef94c7cb9dfd5058bd8a325_FairValueofFinancialInstrumentsTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsByBalanceSheetGroupingDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#FairValueofFinancialInstrumentsByBalanceSheetGroupingDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsByBalanceSheetGroupingDetails" xlink:type="extended" id="i9a81a65e877f416aa6eb63763cc623e5_FairValueofFinancialInstrumentsByBalanceSheetGroupingDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireMarketableSecurities_38d46318-c0bb-4188-bee4-42c697a984a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireMarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_PaymentsToAcquireMarketableSecurities_38d46318-c0bb-4188-bee4-42c697a984a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_2cfef84d-08ac-4750-a778-3e988fc785f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_2cfef84d-08ac-4750-a778-3e988fc785f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_2e5d231e-1606-4c1b-aff9-1d09b2dc0340" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_2cfef84d-08ac-4750-a778-3e988fc785f8" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_2e5d231e-1606-4c1b-aff9-1d09b2dc0340" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsAndNotesReceivableNet_018cc018-5292-4650-8404-984224c905a3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsAndNotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_2cfef84d-08ac-4750-a778-3e988fc785f8" xlink:to="loc_us-gaap_AccountsAndNotesReceivableNet_018cc018-5292-4650-8404-984224c905a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_0c49b1b2-db3c-4cae-b1f2-5306f8cbb67d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_2cfef84d-08ac-4750-a778-3e988fc785f8" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet_0c49b1b2-db3c-4cae-b1f2-5306f8cbb67d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_c7a8b3c1-7cde-4a04-845e-f32dde7884ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_c7a8b3c1-7cde-4a04-845e-f32dde7884ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_FinancialAssetsFairValueDisclosure_6606ea80-4b46-4701-ac69-eed557f43ec6" xlink:href="sui-20210331.xsd#sui_FinancialAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_sui_FinancialAssetsFairValueDisclosure_6606ea80-4b46-4701-ac69-eed557f43ec6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LongTermDebtExcludingSecuredBorrowingsFairValueDisclosure_a09cf110-f634-49d4-ba8f-5a08cc2a7fa2" xlink:href="sui-20210331.xsd#sui_LongTermDebtExcludingSecuredBorrowingsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:to="loc_sui_LongTermDebtExcludingSecuredBorrowingsFairValueDisclosure_a09cf110-f634-49d4-ba8f-5a08cc2a7fa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_494c179b-9584-48b8-bbde-39e1046f3cff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:to="loc_us-gaap_SecuredDebt_494c179b-9584-48b8-bbde-39e1046f3cff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditFairValueDisclosure_3e5cb62b-68f8-4d30-a1c9-29887d4f9345" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LinesOfCreditFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:to="loc_us-gaap_LinesOfCreditFairValueDisclosure_3e5cb62b-68f8-4d30-a1c9-29887d4f9345" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesFairValueDisclosure_edacb15e-8f57-42ed-9478-8fa7242d5fa1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_939b9e78-b961-45ff-8f4e-461bf6c62036" xlink:to="loc_us-gaap_OtherLiabilitiesFairValueDisclosure_edacb15e-8f57-42ed-9478-8fa7242d5fa1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_94e9cec3-6334-469a-9c4f-3e5e1b81fbe7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_94e9cec3-6334-469a-9c4f-3e5e1b81fbe7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_00d5b037-7f80-4d5c-8183-889363e41881" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_00d5b037-7f80-4d5c-8183-889363e41881" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtFairValueOtherChangesInFairValue_f411e499-d84f-4e0f-82a7-9d41728a212f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ServicingAssetAtFairValueOtherChangesInFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_ServicingAssetAtFairValueOtherChangesInFairValue_f411e499-d84f-4e0f-82a7-9d41728a212f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InvestmentFairValueAdjustment_7849c875-ba9f-4c02-a39b-5ddbedb08a52" xlink:href="sui-20210331.xsd#sui_InvestmentFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_sui_InvestmentFairValueAdjustment_7849c875-ba9f-4c02-a39b-5ddbedb08a52" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1570d470-5df8-4441-a0d3-51a6751dede8" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_5850273d-c91b-47e5-ab7d-36514b6a7b8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_FinancialInstrumentAxis_5850273d-c91b-47e5-ab7d-36514b6a7b8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5850273d-c91b-47e5-ab7d-36514b6a7b8d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5850273d-c91b-47e5-ab7d-36514b6a7b8d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5850273d-c91b-47e5-ab7d-36514b6a7b8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8ef7ecf9-1c7b-48f6-ad84-50c01770b0f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5850273d-c91b-47e5-ab7d-36514b6a7b8d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8ef7ecf9-1c7b-48f6-ad84-50c01770b0f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarketableSecuritiesMember_11e0b9bf-e43e-4a43-bb04-78590a0c3e1b" xlink:href="sui-20210331.xsd#sui_MarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8ef7ecf9-1c7b-48f6-ad84-50c01770b0f3" xlink:to="loc_sui_MarketableSecuritiesMember_11e0b9bf-e43e-4a43-bb04-78590a0c3e1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_0f7ac2a7-4a77-4424-9206-8d0511f2bb33" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_0f7ac2a7-4a77-4424-9206-8d0511f2bb33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0f7ac2a7-4a77-4424-9206-8d0511f2bb33_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_0f7ac2a7-4a77-4424-9206-8d0511f2bb33" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0f7ac2a7-4a77-4424-9206-8d0511f2bb33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4367230e-2ed5-49a6-8161-463a04848bc8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_0f7ac2a7-4a77-4424-9206-8d0511f2bb33" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4367230e-2ed5-49a6-8161-463a04848bc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bf5f05d1-4a0a-4b3c-a00b-3ac9903c1e0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4367230e-2ed5-49a6-8161-463a04848bc8" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bf5f05d1-4a0a-4b3c-a00b-3ac9903c1e0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_a65ea8d9-4582-4b24-be20-68011a5d8cc8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bf5f05d1-4a0a-4b3c-a00b-3ac9903c1e0a" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_a65ea8d9-4582-4b24-be20-68011a5d8cc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_b646cbb4-5448-46c5-a17b-2434bc58fae7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bf5f05d1-4a0a-4b3c-a00b-3ac9903c1e0a" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_b646cbb4-5448-46c5-a17b-2434bc58fae7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_18104fd7-0e12-492a-9211-1a74f908e8e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_18104fd7-0e12-492a-9211-1a74f908e8e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_18104fd7-0e12-492a-9211-1a74f908e8e4_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_18104fd7-0e12-492a-9211-1a74f908e8e4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_18104fd7-0e12-492a-9211-1a74f908e8e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3cc16cee-342c-4a91-94b3-ba725e676603" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_18104fd7-0e12-492a-9211-1a74f908e8e4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3cc16cee-342c-4a91-94b3-ba725e676603" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_486788ba-792a-498b-9090-a0da38058c38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3cc16cee-342c-4a91-94b3-ba725e676603" xlink:to="loc_us-gaap_SecuredDebtMember_486788ba-792a-498b-9090-a0da38058c38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e92c3b9e-2294-4c82-8d59-67f11c0b50ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e92c3b9e-2294-4c82-8d59-67f11c0b50ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_e92c3b9e-2294-4c82-8d59-67f11c0b50ef_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e92c3b9e-2294-4c82-8d59-67f11c0b50ef" xlink:to="loc_us-gaap_ReceivableTypeDomain_e92c3b9e-2294-4c82-8d59-67f11c0b50ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e92c3b9e-2294-4c82-8d59-67f11c0b50ef" xlink:to="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_8f6aee7b-d963-4c2d-ba99-00dee048a53d" xlink:href="sui-20210331.xsd#sui_InstallmentNotesReceivableOnManufacturedHomesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:to="loc_sui_InstallmentNotesReceivableOnManufacturedHomesNetMember_8f6aee7b-d963-4c2d-ba99-00dee048a53d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CollateralizedReceivablesMember_0c8e1d12-0e43-4997-acfa-72011a440f7c" xlink:href="sui-20210331.xsd#sui_CollateralizedReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:to="loc_sui_CollateralizedReceivablesMember_0c8e1d12-0e43-4997-acfa-72011a440f7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NotesReceivableFromRealEstateDevelopersMember_1c7325e0-1f18-472d-ac2d-056a0f9f19e1" xlink:href="sui-20210331.xsd#sui_NotesReceivableFromRealEstateDevelopersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:to="loc_sui_NotesReceivableFromRealEstateDevelopersMember_1c7325e0-1f18-472d-ac2d-056a0f9f19e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherContingentLiabilitiesContingentConsiderationMember_4348d055-a288-4f8c-9a84-f363f5f37da4" xlink:href="sui-20210331.xsd#sui_OtherContingentLiabilitiesContingentConsiderationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_5dc8232c-5339-4513-bab2-64071bf5c636" xlink:to="loc_sui_OtherContingentLiabilitiesContingentConsiderationMember_4348d055-a288-4f8c-9a84-f363f5f37da4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e3d31659-f152-4259-8688-adbad478318a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e3d31659-f152-4259-8688-adbad478318a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_e3d31659-f152-4259-8688-adbad478318a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e3d31659-f152-4259-8688-adbad478318a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_e3d31659-f152-4259-8688-adbad478318a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe7d8e6d-618a-47ff-aad5-52261864426d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e3d31659-f152-4259-8688-adbad478318a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe7d8e6d-618a-47ff-aad5-52261864426d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_743205d3-335d-4c54-9746-9e435e36ecef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe7d8e6d-618a-47ff-aad5-52261864426d" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_743205d3-335d-4c54-9746-9e435e36ecef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d55f4939-41d5-4ccb-b4d2-195088275288" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d55f4939-41d5-4ccb-b4d2-195088275288" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d55f4939-41d5-4ccb-b4d2-195088275288_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d55f4939-41d5-4ccb-b4d2-195088275288" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d55f4939-41d5-4ccb-b4d2-195088275288_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8b3349b2-dbe8-46da-a72c-b791c25d98c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d55f4939-41d5-4ccb-b4d2-195088275288" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8b3349b2-dbe8-46da-a72c-b791c25d98c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_f0ab7c3e-10de-402f-a681-62cf16c6d3c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8b3349b2-dbe8-46da-a72c-b791c25d98c0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_f0ab7c3e-10de-402f-a681-62cf16c6d3c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_5b04f227-0152-4bc1-94b6-d77f20915893" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8b3349b2-dbe8-46da-a72c-b791c25d98c0" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_5b04f227-0152-4bc1-94b6-d77f20915893" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_2367cd88-373f-40a0-a63c-89bd55a84ee4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8b3349b2-dbe8-46da-a72c-b791c25d98c0" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_2367cd88-373f-40a0-a63c-89bd55a84ee4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:href="sui-20210331.xsd#sui_ChangesInFairValueLevel3Axis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a8e32f8b-150e-4533-84f7-60f20c42c319" xlink:to="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ChangesInFairValueLevel3Domain_2543b703-07ef-4a38-a33a-9f4402f1a130_default" xlink:href="sui-20210331.xsd#sui_ChangesInFairValueLevel3Domain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_ChangesInFairValueLevel3Domain_2543b703-07ef-4a38-a33a-9f4402f1a130_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ChangesInFairValueLevel3Domain_c282973d-0b0e-45ab-9adf-a3ccad55fb6c" xlink:href="sui-20210331.xsd#sui_ChangesInFairValueLevel3Domain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_ChangesInFairValueLevel3Domain_c282973d-0b0e-45ab-9adf-a3ccad55fb6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TransferToLevel3Member_638dec14-526a-402a-b14b-a3feb0401d25" xlink:href="sui-20210331.xsd#sui_TransferToLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_TransferToLevel3Member_638dec14-526a-402a-b14b-a3feb0401d25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TransferOutOfLevel3Member_697b28ec-4e9e-4e15-b692-f25a2a415984" xlink:href="sui-20210331.xsd#sui_TransferOutOfLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_TransferOutOfLevel3Member_697b28ec-4e9e-4e15-b692-f25a2a415984" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NetEarningsLossMember_d3c27da7-5518-4b27-8e65-c1a5d61b8676" xlink:href="sui-20210331.xsd#sui_NetEarningsLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_NetEarningsLossMember_d3c27da7-5518-4b27-8e65-c1a5d61b8676" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PurchasesAndIssuancesMember_f7003d82-0cd9-4f44-a47b-522d0aca3fa0" xlink:href="sui-20210331.xsd#sui_PurchasesAndIssuancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_PurchasesAndIssuancesMember_f7003d82-0cd9-4f44-a47b-522d0aca3fa0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SalesAndSettlementsMember_7e97c816-f2d0-4fb1-9793-c966992eb487" xlink:href="sui-20210331.xsd#sui_SalesAndSettlementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_SalesAndSettlementsMember_7e97c816-f2d0-4fb1-9793-c966992eb487" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OtherAdjustmentsMember_9512583a-48ce-4dee-8fc5-933901fb8c01" xlink:href="sui-20210331.xsd#sui_OtherAdjustmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_sui_ChangesInFairValueLevel3Axis_2543b703-07ef-4a38-a33a-9f4402f1a130" xlink:to="loc_sui_OtherAdjustmentsMember_9512583a-48ce-4dee-8fc5-933901fb8c01" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsMarketableSecuritiesDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#FairValueofFinancialInstrumentsMarketableSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/FairValueofFinancialInstrumentsMarketableSecuritiesDetails" xlink:type="extended" id="i3e30f428c0f24034aee847408764d828_FairValueofFinancialInstrumentsMarketableSecuritiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InvestmentAdditionalPurchase_c1792b06-58fa-4b69-917f-67f5fd4dff8d" xlink:href="sui-20210331.xsd#sui_InvestmentAdditionalPurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_sui_InvestmentAdditionalPurchase_c1792b06-58fa-4b69-917f-67f5fd4dff8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_f5bdaed8-f176-49b4-8ee0-fd1789719324" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_f5bdaed8-f176-49b4-8ee0-fd1789719324" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_a7365f91-9032-498a-845d-450ae65b1910" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InvestmentFairValueAdjustment_d8e88b6b-5d24-4739-8685-f57c643007a3" xlink:href="sui-20210331.xsd#sui_InvestmentFairValueAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_sui_InvestmentFairValueAdjustment_d8e88b6b-5d24-4739-8685-f57c643007a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_InvestmentForeignCurrentTranslationAdjustment_a1282808-6e0e-4189-8725-818c57a73fd5" xlink:href="sui-20210331.xsd#sui_InvestmentForeignCurrentTranslationAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_sui_InvestmentForeignCurrentTranslationAdjustment_a1282808-6e0e-4189-8725-818c57a73fd5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan_88dc192d-2f7d-40b0-8120-450dff7b2f82" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan_88dc192d-2f7d-40b0-8120-450dff7b2f82" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TaxWitholdingsonDistributionsfromInvestment_283f73eb-3f2d-4dc3-ba1b-34024b358b59" xlink:href="sui-20210331.xsd#sui_TaxWitholdingsonDistributionsfromInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_sui_TaxWitholdingsonDistributionsfromInvestment_283f73eb-3f2d-4dc3-ba1b-34024b358b59" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_dea98bdd-7493-4fc5-a76f-4f2633df4c42" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_8828ac7e-d2f4-40e0-9282-a5e711f45f0a" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_dea98bdd-7493-4fc5-a76f-4f2633df4c42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_7595777d-bf14-4b6f-80ba-84dc495d5f6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_dea98bdd-7493-4fc5-a76f-4f2633df4c42" xlink:to="loc_us-gaap_FinancialInstrumentAxis_7595777d-bf14-4b6f-80ba-84dc495d5f6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7595777d-bf14-4b6f-80ba-84dc495d5f6f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7595777d-bf14-4b6f-80ba-84dc495d5f6f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7595777d-bf14-4b6f-80ba-84dc495d5f6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c6b11532-a28d-4a86-890d-ec246ff691ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7595777d-bf14-4b6f-80ba-84dc495d5f6f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c6b11532-a28d-4a86-890d-ec246ff691ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_MarketableSecuritiesMember_48b8541e-67a4-49e2-808f-37d76c214eb2" xlink:href="sui-20210331.xsd#sui_MarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c6b11532-a28d-4a86-890d-ec246ff691ac" xlink:to="loc_sui_MarketableSecuritiesMember_48b8541e-67a4-49e2-808f-37d76c214eb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d146e32d-1be7-49a9-bcfe-482d73a17cad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_dea98bdd-7493-4fc5-a76f-4f2633df4c42" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d146e32d-1be7-49a9-bcfe-482d73a17cad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_d146e32d-1be7-49a9-bcfe-482d73a17cad_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d146e32d-1be7-49a9-bcfe-482d73a17cad" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_d146e32d-1be7-49a9-bcfe-482d73a17cad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_dea9ad4f-2a7a-44de-9b06-1aade706f6dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d146e32d-1be7-49a9-bcfe-482d73a17cad" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_dea9ad4f-2a7a-44de-9b06-1aade706f6dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_92722fa3-1bec-45b2-95fb-3a63d4440604" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_dea9ad4f-2a7a-44de-9b06-1aade706f6dc" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_92722fa3-1bec-45b2-95fb-3a63d4440604" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/CommitmentsAndContingencies" xlink:type="simple" xlink:href="sui-20210331.xsd#CommitmentsAndContingencies"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/CommitmentsAndContingencies" xlink:type="extended" id="ib847138ba0b647c28807db45aac8ff70_CommitmentsAndContingencies"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/Leases" xlink:type="simple" xlink:href="sui-20210331.xsd#Leases"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/Leases" xlink:type="extended" id="id3baf20ead2543cb8c4155d5a174bdcc_Leases"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/LeasesTables" xlink:type="simple" xlink:href="sui-20210331.xsd#LeasesTables"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/LeasesTables" xlink:type="extended" id="i4878724896ab45a887991d201a526182_LeasesTables"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#LeasesFutureMinimumLeasePaymentsDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="extended" id="ic595fafe6e9d4d1ba8ded40e59151182_LeasesFutureMinimumLeasePaymentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_83e42243-a441-495b-b44b-60411c9fb7a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_83e42243-a441-495b-b44b-60411c9fb7a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_771a5aef-7650-4dd0-a6d6-7222b6c9311c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_771a5aef-7650-4dd0-a6d6-7222b6c9311c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_3a0cef79-c872-4367-9713-f4d821e18b5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_3a0cef79-c872-4367-9713-f4d821e18b5a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_4ab600d6-c0df-4f06-be65-8f8b67134725" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_4ab600d6-c0df-4f06-be65-8f8b67134725" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_06b79ca8-bd25-430b-940a-12262231459c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_06b79ca8-bd25-430b-940a-12262231459c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_bf943aa8-41fd-421c-a3bd-50b84a8e0e61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_bf943aa8-41fd-421c-a3bd-50b84a8e0e61" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_8d724371-1099-41e2-adc0-5afb9c890c61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_8d724371-1099-41e2-adc0-5afb9c890c61" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_4b89af0f-920f-41b0-91c0-7ed9e780b8d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_164b4cd2-3fbb-497b-97dc-3985cd5ba236" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_4b89af0f-920f-41b0-91c0-7ed9e780b8d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/LeasesAdditionalInformationDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#LeasesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/LeasesAdditionalInformationDetails" xlink:type="extended" id="i4e5f15eeae894ad881006a559fd81ca7_LeasesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_aa3ca496-e7e8-4f24-955c-97379c997f51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_OperatingLeaseLiability_aa3ca496-e7e8-4f24-955c-97379c997f51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_953dbda1-461a-4ea8-93bc-7c7001938c99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_FinanceLeaseLiability_953dbda1-461a-4ea8-93bc-7c7001938c99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LesseeOperatingLeaseLeaseNotYetCommencedValue_38bdcf7c-b602-4fcf-b967-871a0d0edfcc" xlink:href="sui-20210331.xsd#sui_LesseeOperatingLeaseLeaseNotYetCommencedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_sui_LesseeOperatingLeaseLeaseNotYetCommencedValue_38bdcf7c-b602-4fcf-b967-871a0d0edfcc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_4757d88f-9fa1-47bf-8ba3-87b0de76a35a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_4757d88f-9fa1-47bf-8ba3-87b0de76a35a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_e6de0445-f3a2-4be9-8b08-925057d4c0eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_e6de0445-f3a2-4be9-8b08-925057d4c0eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_6096d720-710a-421c-a3fb-e546889cad23" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_6096d720-710a-421c-a3fb-e546889cad23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_LesseeOperatingLeaseGrossBaseRent_0e0ec841-0bef-4c95-a31b-43096843e00c" xlink:href="sui-20210331.xsd#sui_LesseeOperatingLeaseGrossBaseRent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_sui_LesseeOperatingLeaseGrossBaseRent_0e0ec841-0bef-4c95-a31b-43096843e00c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseIncome_a4389406-1daa-4384-a189-4b1da7731454" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_LeaseIncome_a4389406-1daa-4384-a189-4b1da7731454" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseIncome_917e3f34-0128-423a-953e-f93fde79147f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableLeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_VariableLeaseIncome_917e3f34-0128-423a-953e-f93fde79147f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_PercentofOperatingLeasesWhereCompanyistheLessor_afed2b35-6613-4d7e-a80e-924f178edf67" xlink:href="sui-20210331.xsd#sui_PercentofOperatingLeasesWhereCompanyistheLessor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_sui_PercentofOperatingLeasesWhereCompanyistheLessor_afed2b35-6613-4d7e-a80e-924f178edf67" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_1407ff6a-f71f-49b4-9afb-00612840e925" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f433a69-66ab-4dc6-a448-34c27f596583" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_1407ff6a-f71f-49b4-9afb-00612840e925" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_1407ff6a-f71f-49b4-9afb-00612840e925" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060" xlink:to="loc_us-gaap_RelatedPartyDomain_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_aedbfe8e-8b90-4c1d-8ffa-21c9c811a21d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_2cc92e9d-e4fc-47b8-ad4c-ed742cf3c060" xlink:to="loc_us-gaap_RelatedPartyDomain_aedbfe8e-8b90-4c1d-8ffa-21c9c811a21d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ChiefExecutiveOfficerMember_eb17a330-c119-4a08-b825-9c968b2a472e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_aedbfe8e-8b90-4c1d-8ffa-21c9c811a21d" xlink:to="loc_srt_ChiefExecutiveOfficerMember_eb17a330-c119-4a08-b825-9c968b2a472e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_fad31ac9-7540-4aca-9661-68412ebb39d1" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_1407ff6a-f71f-49b4-9afb-00612840e925" xlink:to="loc_dei_LegalEntityAxis_fad31ac9-7540-4aca-9661-68412ebb39d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_fad31ac9-7540-4aca-9661-68412ebb39d1_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_fad31ac9-7540-4aca-9661-68412ebb39d1" xlink:to="loc_dei_EntityDomain_fad31ac9-7540-4aca-9661-68412ebb39d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_765b8692-b43b-49d1-8d35-ed9312009e84" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_fad31ac9-7540-4aca-9661-68412ebb39d1" xlink:to="loc_dei_EntityDomain_765b8692-b43b-49d1-8d35-ed9312009e84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_AmericanCenterMember_01eb23c6-eb57-4d48-9029-9fdb7e7ea679" xlink:href="sui-20210331.xsd#sui_AmericanCenterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_765b8692-b43b-49d1-8d35-ed9312009e84" xlink:to="loc_sui_AmericanCenterMember_01eb23c6-eb57-4d48-9029-9fdb7e7ea679" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81b7fc95-f1e7-4789-8e14-43a14caec71b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_1407ff6a-f71f-49b4-9afb-00612840e925" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81b7fc95-f1e7-4789-8e14-43a14caec71b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_81b7fc95-f1e7-4789-8e14-43a14caec71b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81b7fc95-f1e7-4789-8e14-43a14caec71b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_81b7fc95-f1e7-4789-8e14-43a14caec71b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_931d257e-52bf-4bf5-b748-fba0a854b77e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_81b7fc95-f1e7-4789-8e14-43a14caec71b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_931d257e-52bf-4bf5-b748-fba0a854b77e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BelowMarketLeasesMember_a8e1d1f3-b235-41ba-9175-ce6e4e61278b" xlink:href="sui-20210331.xsd#sui_BelowMarketLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_931d257e-52bf-4bf5-b748-fba0a854b77e" xlink:to="loc_sui_BelowMarketLeasesMember_a8e1d1f3-b235-41ba-9175-ce6e4e61278b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/LeasesLeaseExpenseDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#LeasesLeaseExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/LeasesLeaseExpenseDetails" xlink:type="extended" id="i9781f7246e7b4a3f997bfbe03a66d781_LeasesLeaseExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesIncomeStatementAmortizationExpense_2b76af3e-0d1e-42d7-8336-1ad858d09db2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalLeasesIncomeStatementAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_CapitalLeasesIncomeStatementAmortizationExpense_2b76af3e-0d1e-42d7-8336-1ad858d09db2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesIncomeStatementInterestExpense_8d78a2e0-08c8-4877-96f4-6b76bfd4edae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalLeasesIncomeStatementInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_CapitalLeasesIncomeStatementInterestExpense_8d78a2e0-08c8-4877-96f4-6b76bfd4edae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesRentExpenseNet_a08130a9-3f74-4a48-bf66-1514a7ed68a4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeasesRentExpenseNet_a08130a9-3f74-4a48-bf66-1514a7ed68a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_c13944c9-320e-463d-ba89-8bfa7a4339f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_AdjustmentForAmortization_c13944c9-320e-463d-ba89-8bfa7a4339f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_a3f6468c-cd07-4195-a035-997f0213f629" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_a3f6468c-cd07-4195-a035-997f0213f629" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_c2000b16-cbb4-4c98-92b6-4ee24bfa7e36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_c2000b16-cbb4-4c98-92b6-4ee24bfa7e36" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_868d4635-8b14-41a0-8260-111c9a0aa6e3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeaseCost_868d4635-8b14-41a0-8260-111c9a0aa6e3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_68d3634a-f054-43c6-a998-1a9f131b5378" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_VariableLeaseCost_68d3634a-f054-43c6-a998-1a9f131b5378" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_e054227f-76bc-4e25-b5c7-a2d6e112aebe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_ShortTermLeaseCost_e054227f-76bc-4e25-b5c7-a2d6e112aebe" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_ca3b42b5-a8ec-46b4-85ed-995440d9cc07" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_LeaseCost_ca3b42b5-a8ec-46b4-85ed-995440d9cc07" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_e878afdd-f47a-4ab9-874c-952dde5bdc81" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeasePayments_e878afdd-f47a-4ab9-874c-952dde5bdc81" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_736b6ee1-a9ba-4686-85ec-a9767851f114" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_736b6ee1-a9ba-4686-85ec-a9767851f114" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_52350140-ccc1-4652-aed5-58baa84d8d6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_52350140-ccc1-4652-aed5-58baa84d8d6a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasedAssetsGross_7e6294b7-24f2-40fc-baf2-348e4ae818dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalLeasedAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_CapitalLeasedAssetsGross_7e6294b7-24f2-40fc-baf2-348e4ae818dc" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RightofUseAssetObtainedinExchangeforNewOperatingLeaseLiability_36627bf1-2104-419d-92bf-0a4cefd52840" xlink:href="sui-20210331.xsd#sui_RightofUseAssetObtainedinExchangeforNewOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_sui_RightofUseAssetObtainedinExchangeforNewOperatingLeaseLiability_36627bf1-2104-419d-92bf-0a4cefd52840" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_cb2a7114-a8b0-438f-9ba3-e7d840052f92" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_cb2a7114-a8b0-438f-9ba3-e7d840052f92" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BelowMarketLeaseNet_095e7e2d-a246-4561-804f-734de0ed7421" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BelowMarketLeaseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_BelowMarketLeaseNet_095e7e2d-a246-4561-804f-734de0ed7421" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_caf68baa-fada-4e8c-b2e0-f3e190d813a7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_caf68baa-fada-4e8c-b2e0-f3e190d813a7" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_2645ee53-f149-4cec-9740-76bfe0d25d0e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_2645ee53-f149-4cec-9740-76bfe0d25d0e" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_95a8a3ff-8727-49c0-8bc5-960cb3203140" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_95a8a3ff-8727-49c0-8bc5-960cb3203140" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_8e41e333-9484-4949-af3e-97de682f2903" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_8e41e333-9484-4949-af3e-97de682f2903" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_ba060038-3f9b-414a-bd64-c90611621b32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_FinanceLeaseLiability_ba060038-3f9b-414a-bd64-c90611621b32" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeaseObligations_30ed60fb-015c-4fe8-b014-035e1967a6e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_CapitalLeaseObligations_30ed60fb-015c-4fe8-b014-035e1967a6e2" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_dd9988a6-73a0-4e7d-bd24-37f9e74e8188" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_OperatingLeaseLiability_dd9988a6-73a0-4e7d-bd24-37f9e74e8188" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_OperatingAndFinanceLeasePayments_317609f0-c441-40bb-9d5d-f00cbd32e70d" xlink:href="sui-20210331.xsd#sui_OperatingAndFinanceLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_sui_OperatingAndFinanceLeasePayments_317609f0-c441-40bb-9d5d-f00cbd32e70d" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_e91b8ab3-1ec4-41d6-b296-55a4b99e5486" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_df2fa45f-ee60-465d-8424-cfe3dd58b5b4" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_e91b8ab3-1ec4-41d6-b296-55a4b99e5486" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_18e4cd11-b702-4e19-bd82-dbb97be9c15e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e91b8ab3-1ec4-41d6-b296-55a4b99e5486" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_18e4cd11-b702-4e19-bd82-dbb97be9c15e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_18e4cd11-b702-4e19-bd82-dbb97be9c15e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_18e4cd11-b702-4e19-bd82-dbb97be9c15e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_18e4cd11-b702-4e19-bd82-dbb97be9c15e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31228b3b-7f7e-4603-b277-921aae3caca4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_18e4cd11-b702-4e19-bd82-dbb97be9c15e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31228b3b-7f7e-4603-b277-921aae3caca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BelowMarketLeasesMember_c4729e87-ae80-401a-8137-871f7143434d" xlink:href="sui-20210331.xsd#sui_BelowMarketLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_31228b3b-7f7e-4603-b277-921aae3caca4" xlink:to="loc_sui_BelowMarketLeasesMember_c4729e87-ae80-401a-8137-871f7143434d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.suncommunities.com/role/RecentAccountingPronouncements" xlink:type="simple" xlink:href="sui-20210331.xsd#RecentAccountingPronouncements"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/RecentAccountingPronouncements" xlink:type="extended" id="i7b7f8db35d854445b298409ef2b8963e_RecentAccountingPronouncements"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SubsequentEvents" xlink:type="simple" xlink:href="sui-20210331.xsd#SubsequentEvents"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SubsequentEvents" xlink:type="extended" id="i6d26374cfa1f4add82f8aa580caa7873_SubsequentEvents"/>
  <link:roleRef roleURI="http://www.suncommunities.com/role/SubsequentEventDetails" xlink:type="simple" xlink:href="sui-20210331.xsd#SubsequentEventDetails"/>
  <link:definitionLink xlink:role="http://www.suncommunities.com/role/SubsequentEventDetails" xlink:type="extended" id="i6fda32e7b8c04706b2562af0cd8cb023_SubsequentEventDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfDevelopedRecreationalVehicleSitesAcquired_68fca9cd-321e-416b-a84d-6a9ac63b6ce0" xlink:href="sui-20210331.xsd#sui_NumberOfDevelopedRecreationalVehicleSitesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_NumberOfDevelopedRecreationalVehicleSitesAcquired_68fca9cd-321e-416b-a84d-6a9ac63b6ce0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberOfExpansionRecreationalVehicleSitesAcquired_28de7129-574f-40d8-a20c-5e9c91431265" xlink:href="sui-20210331.xsd#sui_NumberOfExpansionRecreationalVehicleSitesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_NumberOfExpansionRecreationalVehicleSitesAcquired_28de7129-574f-40d8-a20c-5e9c91431265" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_de5a1c52-4f80-44ed-b60a-54aefc74cb3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_de5a1c52-4f80-44ed-b60a-54aefc74cb3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_NumberofMHSites_3ca7e7c6-d475-4495-ae42-e069ea786faa" xlink:href="sui-20210331.xsd#sui_NumberofMHSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_NumberofMHSites_3ca7e7c6-d475-4495-ae42-e069ea786faa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_93a1d037-2576-4708-8c0d-d50cb5ee825f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_93a1d037-2576-4708-8c0d-d50cb5ee825f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_67225f36-99f0-4491-934f-5b039639b14c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_67225f36-99f0-4491-934f-5b039639b14c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfUnitsInRealEstateProperty_7f50e7e6-a288-45c9-bbc3-9ca16efee194" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfUnitsInRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_NumberOfUnitsInRealEstateProperty_7f50e7e6-a288-45c9-bbc3-9ca16efee194" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DebtInstrumentConvertibleNumberOfEquityInstrumentsAffectedAndOutstanding_543af604-e7a2-4012-808f-206819c53496" xlink:href="sui-20210331.xsd#sui_DebtInstrumentConvertibleNumberOfEquityInstrumentsAffectedAndOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_DebtInstrumentConvertibleNumberOfEquityInstrumentsAffectedAndOutstanding_543af604-e7a2-4012-808f-206819c53496" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityIssuancePrice_c8c8020d-d02e-4371-8938-ba5a73e70272" xlink:href="sui-20210331.xsd#sui_TemporaryEquityIssuancePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_TemporaryEquityIssuancePrice_c8c8020d-d02e-4371-8938-ba5a73e70272" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_5f307a46-2fbb-450f-a440-c7ff5600c2a2" xlink:href="sui-20210331.xsd#sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_ConvertiblePreferredStockSharesIssuedPerShareUponConversion_5f307a46-2fbb-450f-a440-c7ff5600c2a2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_3eea6674-5285-45a5-964e-22c117b2187c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_3eea6674-5285-45a5-964e-22c117b2187c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_TemporaryEquityDividendsForTermOnePercentage_7efefb32-e779-4445-8a78-bb320d96bdeb" xlink:href="sui-20210331.xsd#sui_TemporaryEquityDividendsForTermOnePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_sui_TemporaryEquityDividendsForTermOnePercentage_7efefb32-e779-4445-8a78-bb320d96bdeb" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_46e96de6-81eb-420f-9541-a593b3815c8d" xlink:to="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_190dd2cf-2568-4b40-b3a0-cce2d14c48da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_190dd2cf-2568-4b40-b3a0-cce2d14c48da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_190dd2cf-2568-4b40-b3a0-cce2d14c48da_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_190dd2cf-2568-4b40-b3a0-cce2d14c48da" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_190dd2cf-2568-4b40-b3a0-cce2d14c48da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_190dd2cf-2568-4b40-b3a0-cce2d14c48da" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_RVCommunityMember_12d9d3d3-6302-47fe-bce6-800c738cbc37" xlink:href="sui-20210331.xsd#sui_RVCommunityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:to="loc_sui_RVCommunityMember_12d9d3d3-6302-47fe-bce6-800c738cbc37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_HendersonRVCommunityMember_0f098db6-e3e4-4efa-ad6e-6b9e866bebf2" xlink:href="sui-20210331.xsd#sui_HendersonRVCommunityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:to="loc_sui_HendersonRVCommunityMember_0f098db6-e3e4-4efa-ad6e-6b9e866bebf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_DavenportFloridaRVResortMember_9633da83-61b1-44c9-98c9-7f3448fa5345" xlink:href="sui-20210331.xsd#sui_DavenportFloridaRVResortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:to="loc_sui_DavenportFloridaRVResortMember_9633da83-61b1-44c9-98c9-7f3448fa5345" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BrightonMichiganMHCommunityMember_8963ce8d-8ce5-46be-a8a3-821a21750871" xlink:href="sui-20210331.xsd#sui_BrightonMichiganMHCommunityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cccc1f3-e52a-4273-9062-4fba9147e6da" xlink:to="loc_sui_BrightonMichiganMHCommunityMember_8963ce8d-8ce5-46be-a8a3-821a21750871" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_e86a4717-9733-4aae-b8ae-5ff796b3184c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_e86a4717-9733-4aae-b8ae-5ff796b3184c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e86a4717-9733-4aae-b8ae-5ff796b3184c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_e86a4717-9733-4aae-b8ae-5ff796b3184c" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e86a4717-9733-4aae-b8ae-5ff796b3184c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4c0661ab-de2c-442d-9d3b-2ffab4f048e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_e86a4717-9733-4aae-b8ae-5ff796b3184c" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4c0661ab-de2c-442d-9d3b-2ffab4f048e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_CountrysideVillageMember_849ca492-2657-4a11-9c97-4bc5d4c70cac" xlink:href="sui-20210331.xsd#sui_CountrysideVillageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4c0661ab-de2c-442d-9d3b-2ffab4f048e4" xlink:to="loc_sui_CountrysideVillageMember_849ca492-2657-4a11-9c97-4bc5d4c70cac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_74c4e0b5-3669-41ec-a343-9d765a75c3f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_74c4e0b5-3669-41ec-a343-9d765a75c3f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_74c4e0b5-3669-41ec-a343-9d765a75c3f4_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_74c4e0b5-3669-41ec-a343-9d765a75c3f4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_74c4e0b5-3669-41ec-a343-9d765a75c3f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_10069c0f-9595-4eef-977e-cf394cf0051f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_74c4e0b5-3669-41ec-a343-9d765a75c3f4" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_10069c0f-9595-4eef-977e-cf394cf0051f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_53652411-ecfd-44d6-b2ac-53d476f22d55" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_10069c0f-9595-4eef-977e-cf394cf0051f" xlink:to="loc_us-gaap_SubsequentEventMember_53652411-ecfd-44d6-b2ac-53d476f22d55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c213fb01-ed30-4e3a-87c8-a03aaf560692" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_DebtInstrumentAxis_c213fb01-ed30-4e3a-87c8-a03aaf560692" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c213fb01-ed30-4e3a-87c8-a03aaf560692_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c213fb01-ed30-4e3a-87c8-a03aaf560692" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c213fb01-ed30-4e3a-87c8-a03aaf560692_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c65e7141-564e-4a08-b0a6-fa5f6db1b0c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c213fb01-ed30-4e3a-87c8-a03aaf560692" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c65e7141-564e-4a08-b0a6-fa5f6db1b0c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesJPreferredOpUnitsMember_cdc2a842-6525-46f3-a547-f5b99fbfe105" xlink:href="sui-20210331.xsd#sui_SeriesJPreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_c65e7141-564e-4a08-b0a6-fa5f6db1b0c9" xlink:to="loc_sui_SeriesJPreferredOpUnitsMember_cdc2a842-6525-46f3-a547-f5b99fbfe105" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_3545f035-7aa4-4fd7-a016-e58f659228e3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_3545f035-7aa4-4fd7-a016-e58f659228e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3545f035-7aa4-4fd7-a016-e58f659228e3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3545f035-7aa4-4fd7-a016-e58f659228e3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3545f035-7aa4-4fd7-a016-e58f659228e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3e3eee1d-bd27-446b-a693-4c2e5d527504" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_3545f035-7aa4-4fd7-a016-e58f659228e3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3e3eee1d-bd27-446b-a693-4c2e5d527504" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_BrightonPreferredOpUnitsMember_caa486fa-28a8-4f61-adb1-b369a85de534" xlink:href="sui-20210331.xsd#sui_BrightonPreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3e3eee1d-bd27-446b-a693-4c2e5d527504" xlink:to="loc_sui_BrightonPreferredOpUnitsMember_caa486fa-28a8-4f61-adb1-b369a85de534" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a7f51917-4875-4ec8-8d00-6d3930117f96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a7f51917-4875-4ec8-8d00-6d3930117f96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a7f51917-4875-4ec8-8d00-6d3930117f96_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a7f51917-4875-4ec8-8d00-6d3930117f96" xlink:to="loc_us-gaap_ClassOfStockDomain_a7f51917-4875-4ec8-8d00-6d3930117f96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_cbaf6864-ec08-4a01-ac14-ded8f46e0ab1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a7f51917-4875-4ec8-8d00-6d3930117f96" xlink:to="loc_us-gaap_ClassOfStockDomain_cbaf6864-ec08-4a01-ac14-ded8f46e0ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_sui_SeriesJPreferredOpUnitsMember_fb5691d0-2d90-4b89-a6b4-d8b80ec9ca29" xlink:href="sui-20210331.xsd#sui_SeriesJPreferredOpUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_cbaf6864-ec08-4a01-ac14-ded8f46e0ab1" xlink:to="loc_sui_SeriesJPreferredOpUnitsMember_fb5691d0-2d90-4b89-a6b4-d8b80ec9ca29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c0229352-5a89-47d7-b6db-560c1a7b144c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_5f5c30af-e7d2-461c-a988-73f7fe6f00ca" xlink:to="loc_srt_RangeAxis_c0229352-5a89-47d7-b6db-560c1a7b144c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c0229352-5a89-47d7-b6db-560c1a7b144c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c0229352-5a89-47d7-b6db-560c1a7b144c" xlink:to="loc_srt_RangeMember_c0229352-5a89-47d7-b6db-560c1a7b144c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5c825657-7c6b-403d-bd2d-a5f77d8c3721" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c0229352-5a89-47d7-b6db-560c1a7b144c" xlink:to="loc_srt_RangeMember_5c825657-7c6b-403d-bd2d-a5f77d8c3721" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_cbaeab48-db20-44c5-80a5-c98074845128" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5c825657-7c6b-403d-bd2d-a5f77d8c3721" xlink:to="loc_srt_MaximumMember_cbaeab48-db20-44c5-80a5-c98074845128" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a5d07130-3c5a-468b-8e70-14bd54f1259e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5c825657-7c6b-403d-bd2d-a5f77d8c3721" xlink:to="loc_srt_MinimumMember_a5d07130-3c5a-468b-8e70-14bd54f1259e" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
