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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019ef121-6790-73e4-8096-7b446a3f4ee5,g:1b7db5bf-33af-434f-94fb-be53a8d62482-->
<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://machnaturalresources.com/role/CONSOLIDATEDBALANCESHEETSUNAUDITED" xlink:type="simple" xlink:href="mnr-20260630.xsd#CONSOLIDATEDBALANCESHEETSUNAUDITED"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/CONSOLIDATEDBALANCESHEETSUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019ef121-6841-7da1-afc6-caf3cb2b4259" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019ef121-6841-7b08-a243-a1354d562822" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019ef121-6841-7da1-afc6-caf3cb2b4259" xlink:to="loc_us-gaap_StatementTable_019ef121-6841-7b08-a243-a1354d562822" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-6841-72bc-a29f-6cf4484d6a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019ef121-6841-7b08-a243-a1354d562822" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-6841-72bc-a29f-6cf4484d6a7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-6841-72bc-a29f-6cf4484d6a7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-6841-72bc-a29f-6cf4484d6a7e" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-6841-72bc-a29f-6cf4484d6a7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-6841-7a89-b31e-0a79045a9cfd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-6841-72bc-a29f-6cf4484d6a7e" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-6841-7a89-b31e-0a79045a9cfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019ef121-6841-74a3-8224-140cad549976" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-6841-7a89-b31e-0a79045a9cfd" xlink:to="loc_us-gaap_RelatedPartyMember_019ef121-6841-74a3-8224-140cad549976" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019ef121-6841-7abe-b083-4bba15b8047d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-6841-7a89-b31e-0a79045a9cfd" xlink:to="loc_us-gaap_NonrelatedPartyMember_019ef121-6841-7abe-b083-4bba15b8047d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-6841-7da1-afc6-caf3cb2b4259" xlink:to="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019ef121-6841-74d6-8632-30684342f9ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019ef121-6841-74d6-8632-30684342f9ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019ef121-6841-75ad-952e-7cd6023e3987" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019ef121-6841-75ad-952e-7cd6023e3987" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_019ef121-6841-7f7f-b6e2-0d24bce324ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_019ef121-6841-7f7f-b6e2-0d24bce324ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019ef121-6841-7258-95c1-ee2505dfd7b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_InventoryNet_019ef121-6841-7258-95c1-ee2505dfd7b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_019ef121-6841-7e16-a143-fdcf8beded01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_OtherAssetsCurrent_019ef121-6841-7e16-a143-fdcf8beded01" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019ef121-6841-7685-a47b-7de39af5fa89" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019ef121-6841-7848-aae0-a177e48dfe91" xlink:to="loc_us-gaap_AssetsCurrent_019ef121-6841-7685-a47b-7de39af5fa89" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-6841-715a-9e05-19c775645975" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-6841-715a-9e05-19c775645975" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodGross_019ef121-6841-7dcc-afd1-b5d363016e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-6841-715a-9e05-19c775645975" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodGross_019ef121-6841-7dcc-afd1-b5d363016e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodDepletion_019ef121-6841-7966-820f-3ec0f07b754d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodDepletion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-6841-715a-9e05-19c775645975" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodDepletion_019ef121-6841-7966-820f-3ec0f07b754d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodNet_019ef121-6841-7f92-afc2-b5bb17b29407" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-6841-715a-9e05-19c775645975" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodNet_019ef121-6841-7f92-afc2-b5bb17b29407" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-6841-723a-862b-1baaffabe72c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-6841-723a-862b-1baaffabe72c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019ef121-6841-7478-b6c1-7b26a86785b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-6841-723a-862b-1baaffabe72c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019ef121-6841-7478-b6c1-7b26a86785b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019ef121-6841-7ee7-b8a1-e197f6eb14dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-6841-723a-862b-1baaffabe72c" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019ef121-6841-7ee7-b8a1-e197f6eb14dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019ef121-6841-7c7c-b114-d36f81cfe256" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-6841-723a-862b-1baaffabe72c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019ef121-6841-7c7c-b114-d36f81cfe256" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_019ef121-6841-7ff7-9838-7212b29f9a9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_019ef121-6841-7ff7-9838-7212b29f9a9b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019ef121-6841-7937-9f42-f5d4548862a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019ef121-6841-7937-9f42-f5d4548862a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019ef121-6841-748f-beca-6e54274e8814" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019ef121-6841-748f-beca-6e54274e8814" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019ef121-6841-7646-97fd-025fb297fb88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019ef121-6841-7d13-a590-b80b5a218252" xlink:to="loc_us-gaap_Assets_019ef121-6841-7646-97fd-025fb297fb88" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-6841-7da1-afc6-caf3cb2b4259" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019ef121-6841-738e-a9fb-d898eabceebd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_AccountsPayableCurrent_019ef121-6841-738e-a9fb-d898eabceebd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_019ef121-6841-7349-81d2-74d5749579c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_019ef121-6841-7349-81d2-74d5749579c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeCurrent_019ef121-6841-7e61-b8c6-fbdbe6cd3b7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_DeferredIncomeCurrent_019ef121-6841-7e61-b8c6-fbdbe6cd3b7a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_019ef121-6841-72e4-997c-5cd0c331902f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_019ef121-6841-72e4-997c-5cd0c331902f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019ef121-6841-72af-bbc0-023ab3195325" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019ef121-6841-72af-bbc0-023ab3195325" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019ef121-6841-72c2-8e8d-0ef0ec2c8899" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019ef121-6841-7a6c-8655-32437e312123" xlink:to="loc_us-gaap_LiabilitiesCurrent_019ef121-6841-72c2-8e8d-0ef0ec2c8899" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019ef121-6841-72e2-95e2-f4aec57f6910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019ef121-6841-72e2-95e2-f4aec57f6910" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationsNoncurrent_019ef121-6841-7df9-8716-a97cace673d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_AssetRetirementObligationsNoncurrent_019ef121-6841-7df9-8716-a97cace673d8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019ef121-6841-7c62-96b7-d76318eaf7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_019ef121-6841-7c62-96b7-d76318eaf7e5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019ef121-6841-7824-9961-d7b079734a6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019ef121-6841-7824-9961-d7b079734a6c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019ef121-6841-744b-83e8-67f82069b484" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019ef121-6841-744b-83e8-67f82069b484" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrent_019ef121-6841-71e2-b0bc-9dfd8b6abc12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_LiabilitiesNoncurrent_019ef121-6841-71e2-b0bc-9dfd8b6abc12" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019ef121-6841-7344-bd5f-639ca7741136" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019ef121-6841-7344-bd5f-639ca7741136" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAbstract_019ef121-6841-7348-b3f7-3d8a67a7c99f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_PartnersCapitalAbstract_019ef121-6841-7348-b3f7-3d8a67a7c99f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_019ef121-6841-7589-88a2-7986d80d36f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnersCapitalAbstract_019ef121-6841-7348-b3f7-3d8a67a7c99f" xlink:to="loc_us-gaap_PartnersCapital_019ef121-6841-7589-88a2-7986d80d36f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019ef121-6841-7e4f-a52f-3bd634230503" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019ef121-6841-76e9-a974-94212106d666" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019ef121-6841-7e4f-a52f-3bd634230503" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONSUNAUDITED" xlink:type="simple" xlink:href="mnr-20260630.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONSUNAUDITED"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONSUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019ef121-68fe-7c0b-8239-fc9b43c2a02d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_StatementTable_019ef121-68fe-7c0b-8239-fc9b43c2a02d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ef121-68fe-7768-a799-b470a91c9749" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019ef121-68fe-7c0b-8239-fc9b43c2a02d" xlink:to="loc_srt_ProductOrServiceAxis_019ef121-68fe-7768-a799-b470a91c9749" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7768-a799-b470a91c9749_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68fe-7768-a799-b470a91c9749" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7768-a799-b470a91c9749_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68fe-7768-a799-b470a91c9749" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-71b0-a04a-ecc3dbb738a4" xlink:href="mnr-20260630.xsd#mnr_OilGasAndNaturalGasLiquidsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:to="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-71b0-a04a-ecc3dbb738a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_OilAndNaturalGasDerivativesGainLossMember_019ef121-68fe-7fc7-aba3-437ea9d84f77" xlink:href="mnr-20260630.xsd#mnr_OilAndNaturalGasDerivativesGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:to="loc_mnr_OilAndNaturalGasDerivativesGainLossMember_019ef121-68fe-7fc7-aba3-437ea9d84f77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NaturalGasMidstreamMember_019ef121-68fe-7928-acaa-fe1877326744" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NaturalGasMidstreamMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:to="loc_us-gaap_NaturalGasMidstreamMember_019ef121-68fe-7928-acaa-fe1877326744" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019ef121-68fe-75b9-91ec-86a95638a3a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68fe-704d-a644-4ca9e70d6e91" xlink:to="loc_us-gaap_ProductMember_019ef121-68fe-75b9-91ec-86a95638a3a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68fe-7ad0-af84-9e1e22e32c3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019ef121-68fe-7c0b-8239-fc9b43c2a02d" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68fe-7ad0-af84-9e1e22e32c3a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-7ad0-af84-9e1e22e32c3a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68fe-7ad0-af84-9e1e22e32c3a" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-7ad0-af84-9e1e22e32c3a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-76f3-b13c-5b75e67816e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68fe-7ad0-af84-9e1e22e32c3a" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-76f3-b13c-5b75e67816e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019ef121-68fe-7828-b963-2a3bfd0c76ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-76f3-b13c-5b75e67816e6" xlink:to="loc_us-gaap_NonrelatedPartyMember_019ef121-68fe-7828-b963-2a3bfd0c76ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019ef121-68fe-7a8a-b64a-c5fe38fdf98a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-68fe-76f3-b13c-5b75e67816e6" xlink:to="loc_us-gaap_RelatedPartyMember_019ef121-68fe-7a8a-b64a-c5fe38fdf98a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019ef121-68fe-7b4d-827f-3f75b4adf70a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_RevenuesAbstract_019ef121-68fe-7b4d-827f-3f75b4adf70a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019ef121-68fe-70c0-ac5c-8f3563522641" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019ef121-68fe-7b4d-827f-3f75b4adf70a" xlink:to="loc_us-gaap_Revenues_019ef121-68fe-70c0-ac5c-8f3563522641" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019ef121-68fe-7b84-a9bc-dcca1689189f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019ef121-68fe-7b84-a9bc-dcca1689189f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResultsOfOperationsProductionOrLiftingCosts_019ef121-68fe-7dc3-a7f7-2b916e90a3bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResultsOfOperationsProductionOrLiftingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_ResultsOfOperationsProductionOrLiftingCosts_019ef121-68fe-7dc3-a7f7-2b916e90a3bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductionTaxExpense_019ef121-68fe-79db-842f-3ad74ded1a41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductionTaxExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_ProductionTaxExpense_019ef121-68fe-79db-842f-3ad74ded1a41" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepletionOfOilAndGasProperties_019ef121-68fe-7cda-a6c5-b8f15a322d24" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepletionOfOilAndGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_DepletionOfOilAndGasProperties_019ef121-68fe-7cda-a6c5-b8f15a322d24" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDepreciationAndAmortization_019ef121-68fe-7073-93a5-96efb187907b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_OtherDepreciationAndAmortization_019ef121-68fe-7073-93a5-96efb187907b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019ef121-68fe-7797-be8b-5ff01d2c3575" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019ef121-68fe-7797-be8b-5ff01d2c3575" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019ef121-68fe-7e18-92f2-fba3f3df327c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019ef121-68fe-7b02-bc3e-536923678472" xlink:to="loc_us-gaap_CostsAndExpenses_019ef121-68fe-7e18-92f2-fba3f3df327c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019ef121-68fe-77a1-af36-f0f7e9a17b1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_OperatingIncomeLoss_019ef121-68fe-77a1-af36-f0f7e9a17b1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIncomeAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019ef121-68fe-7ae7-b02b-6abc8434b920" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019ef121-68fe-7ae7-b02b-6abc8434b920" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019ef121-68fe-7896-bf05-4163be184e61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019ef121-68fe-7896-bf05-4163be184e61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef121-68fe-78cd-8612-a6881bf67ff2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef121-68fe-78cd-8612-a6881bf67ff2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019ef121-68fe-79e3-8d41-c09b04ec4a66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_019ef121-68fe-71cd-8e69-d509007e6187" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019ef121-68fe-79e3-8d41-c09b04ec4a66" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019ef121-68fe-7420-8259-7d980d9f11b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_NetIncomeLoss_019ef121-68fe-7420-8259-7d980d9f11b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_019ef121-68fe-7d16-819d-6713695266c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_EarningsPerShareAbstract_019ef121-68fe-7d16-819d-6713695266c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019ef121-68fe-7354-b4e1-b09d0f3288a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019ef121-68fe-7d16-819d-6713695266c6" xlink:to="loc_us-gaap_EarningsPerShareBasic_019ef121-68fe-7354-b4e1-b09d0f3288a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019ef121-68fe-73c8-9a41-9cee730268f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019ef121-68fe-7d16-819d-6713695266c6" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019ef121-68fe-73c8-9a41-9cee730268f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019ef121-68fe-70ee-94fd-d110379ea9e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef121-68fe-711a-8444-c199de74e83f" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019ef121-68fe-70ee-94fd-d110379ea9e0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019ef121-68fe-7440-adc6-e7928c2c88e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019ef121-68fe-70ee-94fd-d110379ea9e0" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019ef121-68fe-7440-adc6-e7928c2c88e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019ef121-68fe-71bd-8128-9c0f8b976d1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract_019ef121-68fe-70ee-94fd-d110379ea9e0" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019ef121-68fe-71bd-8128-9c0f8b976d1d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/CONSOLIDATEDSTATEMENTSOFPARTNERSCAPITALUNAUDITED" xlink:type="simple" xlink:href="mnr-20260630.xsd#CONSOLIDATEDSTATEMENTSOFPARTNERSCAPITALUNAUDITED"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/CONSOLIDATEDSTATEMENTSOFPARTNERSCAPITALUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fb650-858d-74ed-b023-bdc1e27d0ffb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fb650-858d-727d-a128-335326bd0748" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fb650-858d-74ed-b023-bdc1e27d0ffb" xlink:to="loc_us-gaap_StatementTable_019fb650-858d-727d-a128-335326bd0748" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019fb650-858d-72f7-bad6-1c868b601a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fb650-858d-727d-a128-335326bd0748" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019fb650-858d-72f7-bad6-1c868b601a0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-72f7-bad6-1c868b601a0d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019fb650-858d-72f7-bad6-1c868b601a0d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-72f7-bad6-1c868b601a0d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-7bb8-b8f4-f49ab49913cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019fb650-858d-72f7-bad6-1c868b601a0d" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-7bb8-b8f4-f49ab49913cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_019fb651-975a-7c91-a2d5-927e7df6c5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-7bb8-b8f4-f49ab49913cd" xlink:to="loc_us-gaap_IPOMember_019fb651-975a-7c91-a2d5-927e7df6c5a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AtTheMarketOfferingMember_019fb650-858d-7c31-9a07-9e38757e153a" xlink:href="mnr-20260630.xsd#mnr_AtTheMarketOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fb650-858d-7bb8-b8f4-f49ab49913cd" xlink:to="loc_mnr_AtTheMarketOfferingMember_019fb650-858d-7c31-9a07-9e38757e153a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPartnersCapitalRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fb650-858d-74ed-b023-bdc1e27d0ffb" xlink:to="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnits_019ef121-68fe-7b26-9056-88cf90499004" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_PartnersCapitalAccountUnits_019ef121-68fe-7b26-9056-88cf90499004" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_019ef121-68fe-725c-a922-0e798f09a1d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_PartnersCapital_019ef121-68fe-725c-a922-0e798f09a1d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019ef121-68fe-707f-a1cb-e61267978da6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_NetIncomeLoss_019ef121-68fe-707f-a1cb-e61267978da6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_019ef121-68fe-7e73-bb7d-43cac9848657" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_019ef121-68fe-7e73-bb7d-43cac9848657" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019ef121-68fe-7399-b0e8-8f598f6e39b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019ef121-68fe-7399-b0e8-8f598f6e39b8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedPaymentArrangementUnitsVestedDuringPeriodNetOfSharesWithheldForTaxWithholdingObligation_019ef121-68fe-76d7-9900-15f7404a2716" xlink:href="mnr-20260630.xsd#mnr_ShareBasedPaymentArrangementUnitsVestedDuringPeriodNetOfSharesWithheldForTaxWithholdingObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_mnr_ShareBasedPaymentArrangementUnitsVestedDuringPeriodNetOfSharesWithheldForTaxWithholdingObligation_019ef121-68fe-76d7-9900-15f7404a2716" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019f1141-0635-725c-833c-87ddd31277d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019f1141-0635-725c-833c-87ddd31277d8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnitsSoldInPublicOffering_019ef121-68fe-7aed-b0e6-5803703888ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountUnitsSoldInPublicOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_us-gaap_PartnersCapitalAccountUnitsSoldInPublicOffering_019ef121-68fe-7aed-b0e6-5803703888ae" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountPublicSaleOfUnitsNetOfUnderwritingFeesAndOfferingExpenses_019fb61e-354b-7ce4-8686-d2b11c5b84db" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountPublicSaleOfUnitsNetOfUnderwritingFeesAndOfferingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_mnr_PartnersCapitalAccountPublicSaleOfUnitsNetOfUnderwritingFeesAndOfferingExpenses_019fb61e-354b-7ce4-8686-d2b11c5b84db" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountUnitsCancelled_019f1141-856c-7e97-a299-0d9a5f0693db" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountUnitsCancelled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_mnr_PartnersCapitalAccountUnitsCancelled_019f1141-856c-7e97-a299-0d9a5f0693db" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountCancelledInAcquisition_019f1141-856c-72bc-a58f-f80024d6b2c5" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountCancelledInAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_019ef121-68fe-7765-ae22-9c234963700b" xlink:to="loc_mnr_PartnersCapitalAccountCancelledInAcquisition_019f1141-856c-72bc-a58f-f80024d6b2c5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnits_019ef121-68fe-7b94-a9f1-46cc94c354b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountUnits"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_019ef121-68fe-7483-b45c-55b4f57470cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapital"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f12a6-aabd-7eaa-9389-862741d33e97" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_srt_MajorCustomersAxis_019f12a6-aabd-7eaa-9389-862741d33e97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-7eaa-9389-862741d33e97_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019f12a6-aabd-7eaa-9389-862741d33e97" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-7eaa-9389-862741d33e97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-782c-bee5-c54f2194e363" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019f12a6-aabd-7eaa-9389-862741d33e97" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-782c-bee5-c54f2194e363" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CustomerOneMember_019f12a6-aabd-72b0-b38d-833479eda7e1" xlink:href="mnr-20260630.xsd#mnr_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-782c-bee5-c54f2194e363" xlink:to="loc_mnr_CustomerOneMember_019f12a6-aabd-72b0-b38d-833479eda7e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CustomerTwoMember_019f12a6-aabd-7acc-86ef-6d5cabfda8e3" xlink:href="mnr-20260630.xsd#mnr_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-782c-bee5-c54f2194e363" xlink:to="loc_mnr_CustomerTwoMember_019f12a6-aabd-7acc-86ef-6d5cabfda8e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CustomerThreeMember_019f83ae-626e-7aee-a82a-e16d1151c720" xlink:href="mnr-20260630.xsd#mnr_CustomerThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f12a6-aabd-782c-bee5-c54f2194e363" xlink:to="loc_mnr_CustomerThreeMember_019f83ae-626e-7aee-a82a-e16d1151c720" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f12a6-aabd-773e-8c39-b5bbd1a54c06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f12a6-aabd-740c-a1ae-3d3d0e0b4f4c" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f12a6-aabd-773e-8c39-b5bbd1a54c06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_JointInterestReceivablesMember_019f12a6-aabd-7f06-ba98-7a5340676049" xlink:href="mnr-20260630.xsd#mnr_JointInterestReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f12a6-aabd-773e-8c39-b5bbd1a54c06" xlink:to="loc_mnr_JointInterestReceivablesMember_019f12a6-aabd-7f06-ba98-7a5340676049" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f12a6-aabd-7901-8da9-63bc42222d0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f12a6-aabd-7901-8da9-63bc42222d0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f12a6-aabd-7901-8da9-63bc42222d0c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f12a6-aabd-7901-8da9-63bc42222d0c" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f12a6-aabd-7901-8da9-63bc42222d0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f12a6-aabd-7e67-938c-4b1bdf5462ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f12a6-aabd-7901-8da9-63bc42222d0c" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f12a6-aabd-7e67-938c-4b1bdf5462ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f12a6-aabd-7b07-bad8-c58ca529c910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f12a6-aabd-7e67-938c-4b1bdf5462ec" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f12a6-aabd-7b07-bad8-c58ca529c910" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f12a7-2053-716a-8561-9db68816e414" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_srt_RangeAxis_019f12a7-2053-716a-8561-9db68816e414" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f12a7-2053-716a-8561-9db68816e414_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f12a7-2053-716a-8561-9db68816e414" xlink:to="loc_srt_RangeMember_019f12a7-2053-716a-8561-9db68816e414_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f12a7-2053-7182-b585-6b39aadf20bf" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f12a7-2053-716a-8561-9db68816e414" xlink:to="loc_srt_RangeMember_019f12a7-2053-7182-b585-6b39aadf20bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f12a7-2053-7c29-9694-f87c5bb14f61" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f12a7-2053-7182-b585-6b39aadf20bf" xlink:to="loc_srt_MinimumMember_019f12a7-2053-7c29-9694-f87c5bb14f61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f12a7-2053-7b2f-a119-20d692a54712" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f12a7-2053-7182-b585-6b39aadf20bf" xlink:to="loc_srt_MaximumMember_019f12a7-2053-7b2f-a119-20d692a54712" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f12a7-be0e-7d64-8c9a-ee2480bc135a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_CreditFacilityAxis_019f12a7-be0e-7d64-8c9a-ee2480bc135a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f12a7-be0e-7d64-8c9a-ee2480bc135a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f12a7-be0e-7d64-8c9a-ee2480bc135a" xlink:to="loc_us-gaap_CreditFacilityDomain_019f12a7-be0e-7d64-8c9a-ee2480bc135a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f12a7-be0e-7243-b2df-2318810ca23b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f12a7-be0e-7d64-8c9a-ee2480bc135a" xlink:to="loc_us-gaap_CreditFacilityDomain_019f12a7-be0e-7243-b2df-2318810ca23b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f12a7-be0e-7178-8bce-547c1ef2665c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f12a7-be0e-7243-b2df-2318810ca23b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f12a7-be0e-7178-8bce-547c1ef2665c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f12a7-be0e-7565-b6eb-b070e30db34f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f12a7-be0e-7565-b6eb-b070e30db34f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f12a7-be0e-7565-b6eb-b070e30db34f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f12a7-be0e-7565-b6eb-b070e30db34f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f12a7-be0e-7565-b6eb-b070e30db34f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f12a7-be0e-7700-84f8-c059d8ac2f91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f12a7-be0e-7565-b6eb-b070e30db34f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f12a7-be0e-7700-84f8-c059d8ac2f91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_NewCreditAgreementMember_019f12a7-be0e-7815-8741-33292fdd5be9" xlink:href="mnr-20260630.xsd#mnr_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f12a7-be0e-7700-84f8-c059d8ac2f91" xlink:to="loc_mnr_NewCreditAgreementMember_019f12a7-be0e-7815-8741-33292fdd5be9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f12a7-be0e-7e68-b2e6-9a2c38b587bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f12a7-be0e-7e68-b2e6-9a2c38b587bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f12a7-be0e-7e68-b2e6-9a2c38b587bc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f12a7-be0e-7e68-b2e6-9a2c38b587bc" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f12a7-be0e-7e68-b2e6-9a2c38b587bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f12a7-be0e-7ad9-b97c-34045cb62f53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f12a7-be0e-7e68-b2e6-9a2c38b587bc" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f12a7-be0e-7ad9-b97c-34045cb62f53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f12a7-be0e-74fd-8f25-f30eacd52e85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f12a7-be0e-7ad9-b97c-34045cb62f53" xlink:to="loc_us-gaap_LineOfCreditMember_019f12a7-be0e-74fd-8f25-f30eacd52e85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-76ba-9ccd-b769588e9b2c" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c" xlink:to="loc_us-gaap_RelatedPartyDomain_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f12a8-20a2-7c9c-a161-9574eb491ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f12a8-20a2-7ea1-b3d4-e2e3cae5766c" xlink:to="loc_us-gaap_RelatedPartyDomain_019f12a8-20a2-7c9c-a161-9574eb491ea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019f12a8-20a2-7089-9ef4-cc7d22414770" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019f12a8-20a2-7c9c-a161-9574eb491ea9" xlink:to="loc_us-gaap_NonrelatedPartyMember_019f12a8-20a2-7089-9ef4-cc7d22414770" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f12a6-aabd-72d0-83d7-5e2921f57eb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f12a6-aabd-72d0-83d7-5e2921f57eb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_019f12a6-aabd-7434-aae8-288bbc7b7075" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_019f12a6-aabd-7434-aae8-288bbc7b7075" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AmortizationExpensePerPhysicalUnitOfProductionAverageExpenseDuringPeriod_019f12a6-e57a-7ced-b057-92334afe2dae" xlink:href="mnr-20260630.xsd#mnr_AmortizationExpensePerPhysicalUnitOfProductionAverageExpenseDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_mnr_AmortizationExpensePerPhysicalUnitOfProductionAverageExpenseDuringPeriod_019f12a6-e57a-7ced-b057-92334afe2dae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNet_019f12a6-e57a-7192-b320-e21dbc96ed52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAmortizationAndAccretionNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNet_019f12a6-e57a-7192-b320-e21dbc96ed52" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfOilAndGasProperties_019f12a7-01f9-7c21-89bb-b066dfcf0456" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfOilAndGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_ImpairmentOfOilAndGasProperties_019f12a7-01f9-7c21-89bb-b066dfcf0456" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f12a7-2053-7746-a989-d9057f204027" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019f12a7-2053-7746-a989-d9057f204027" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019f12a7-2053-7910-b839-42ceb61973c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_Depreciation_019f12a7-2053-7910-b839-42ceb61973c8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019f12a7-2053-71d1-bb7b-c2df825bc098" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019f12a7-2053-71d1-bb7b-c2df825bc098" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019f12a7-be0e-74bf-9646-4a930c9273c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019f12a7-be0e-74bf-9646-4a930c9273c2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019f12a7-be0e-773b-8551-e5c1dbc38255" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019f12a7-be0e-773b-8551-e5c1dbc38255" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019f12a7-be0e-784e-bd29-48c48a24e6ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019f12a7-be0e-784e-bd29-48c48a24e6ce" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedAmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019f12a7-be0e-70f6-ad21-83f84b211941" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedAmortizationOfDebtIssuanceCostsLineOfCreditArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_AccumulatedAmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019f12a7-be0e-70f6-ad21-83f84b211941" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019f12a7-be0e-7f0b-b176-deedc1ee0dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019f12a7-be0e-7f0b-b176-deedc1ee0dd6" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CommodityDeliveryPaymentPeriod_019f12a7-ec22-76f8-94fc-70f0f47c725a" xlink:href="mnr-20260630.xsd#mnr_CommodityDeliveryPaymentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_mnr_CommodityDeliveryPaymentPeriod_019f12a7-ec22-76f8-94fc-70f0f47c725a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019f12a8-20a2-7c51-95bc-3692e7d9eefb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f12a6-aabd-7504-ae51-8f8138e3ac47" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019f12a8-20a2-7c51-95bc-3692e7d9eefb" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofConcentrationsofRiskDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofConcentrationsofRiskDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofConcentrationsofRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_019ef121-68fe-7b76-9757-45eb6afa2f38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-719f-b1be-ce91356019e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019ef121-68fe-7b76-9757-45eb6afa2f38" xlink:to="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-719f-b1be-ce91356019e4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019ef121-68fe-7b29-b901-edb4ecc3b96e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-719f-b1be-ce91356019e4" xlink:to="loc_srt_MajorCustomersAxis_019ef121-68fe-7b29-b901-edb4ecc3b96e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7b29-b901-edb4ecc3b96e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019ef121-68fe-7b29-b901-edb4ecc3b96e" xlink:to="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7b29-b901-edb4ecc3b96e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019ef121-68fe-7b29-b901-edb4ecc3b96e" xlink:to="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PurchaserAMember_019f1296-5742-75e1-8d20-1f25070e62ac" xlink:href="mnr-20260630.xsd#mnr_PurchaserAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:to="loc_mnr_PurchaserAMember_019f1296-5742-75e1-8d20-1f25070e62ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PurchaserBMember_019f1296-5742-78b5-90dd-82405eac37c1" xlink:href="mnr-20260630.xsd#mnr_PurchaserBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:to="loc_mnr_PurchaserBMember_019f1296-5742-78b5-90dd-82405eac37c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PurchaserCMember_019f1296-5742-721e-b335-992a9180de1b" xlink:href="mnr-20260630.xsd#mnr_PurchaserCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:to="loc_mnr_PurchaserCMember_019f1296-5742-721e-b335-992a9180de1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PurchaserDMember_019f83b1-1651-7497-b918-16bb00e06d58" xlink:href="mnr-20260630.xsd#mnr_PurchaserDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef121-68fe-7008-8c32-ce2bae66b56e" xlink:to="loc_mnr_PurchaserDMember_019f83b1-1651-7497-b918-16bb00e06d58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef121-68fe-769b-bc53-20abc57c7cf2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-719f-b1be-ce91356019e4" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef121-68fe-769b-bc53-20abc57c7cf2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef121-68fe-769b-bc53-20abc57c7cf2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef121-68fe-769b-bc53-20abc57c7cf2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef121-68fe-769b-bc53-20abc57c7cf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef121-68fe-7d25-af3b-63396b991788" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef121-68fe-769b-bc53-20abc57c7cf2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef121-68fe-7d25-af3b-63396b991788" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_019ef121-68fe-72a1-9f28-4199964c9e47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef121-68fe-7d25-af3b-63396b991788" xlink:to="loc_us-gaap_SalesRevenueNetMember_019ef121-68fe-72a1-9f28-4199964c9e47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef121-68fe-7ebe-bfea-04a31a3569a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019ef121-68fe-719f-b1be-ce91356019e4" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef121-68fe-7ebe-bfea-04a31a3569a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef121-68fe-7ebe-bfea-04a31a3569a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef121-68fe-7ebe-bfea-04a31a3569a3" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef121-68fe-7ebe-bfea-04a31a3569a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef121-68fe-7a1c-8c4d-60af7714351e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef121-68fe-7ebe-bfea-04a31a3569a3" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef121-68fe-7a1c-8c4d-60af7714351e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019ef121-68fe-749d-92c4-2cc8c959a601" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019ef121-68fe-7a1c-8c4d-60af7714351e" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019ef121-68fe-749d-92c4-2cc8c959a601" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019ef121-68fe-77cc-a71a-de62703d3efd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019ef121-68fe-7b76-9757-45eb6afa2f38" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019ef121-68fe-77cc-a71a-de62703d3efd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofRevenueDisaggregationDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofRevenueDisaggregationDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/BasisofPresentationandSummaryofSignificantAccountingPoliciesScheduleofRevenueDisaggregationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef121-68fe-7c42-b420-14a6d3e19ee3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019ef121-68fe-77e4-bf6b-d88deff344d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef121-68fe-7c42-b420-14a6d3e19ee3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019ef121-68fe-77e4-bf6b-d88deff344d6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ef121-68fe-7cd7-be84-8530994dc875" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019ef121-68fe-77e4-bf6b-d88deff344d6" xlink:to="loc_srt_ProductOrServiceAxis_019ef121-68fe-7cd7-be84-8530994dc875" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7cd7-be84-8530994dc875_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68fe-7cd7-be84-8530994dc875" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7cd7-be84-8530994dc875_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7352-928d-e014c27ef4ab" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68fe-7cd7-be84-8530994dc875" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7352-928d-e014c27ef4ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-77b2-aac5-c1b87a94f1fe" xlink:href="mnr-20260630.xsd#mnr_OilGasAndNaturalGasLiquidsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68fe-7352-928d-e014c27ef4ab" xlink:to="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-77b2-aac5-c1b87a94f1fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_OilGasAndNaturalGasLiquidsGrossMember_019ef121-68fe-70de-abd5-8887c6019013" xlink:href="mnr-20260630.xsd#mnr_OilGasAndNaturalGasLiquidsGrossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-77b2-aac5-c1b87a94f1fe" xlink:to="loc_mnr_OilGasAndNaturalGasLiquidsGrossMember_019ef121-68fe-70de-abd5-8887c6019013" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OilReservesMember_019ef121-68fe-7023-96b6-1f83cfb50e52" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_OilReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_OilGasAndNaturalGasLiquidsGrossMember_019ef121-68fe-70de-abd5-8887c6019013" xlink:to="loc_srt_OilReservesMember_019ef121-68fe-7023-96b6-1f83cfb50e52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_019ef121-68fe-7ca9-8a3d-413e23c8366b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_OilGasAndNaturalGasLiquidsGrossMember_019ef121-68fe-70de-abd5-8887c6019013" xlink:to="loc_srt_NaturalGasReservesMember_019ef121-68fe-7ca9-8a3d-413e23c8366b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasLiquidsReservesMember_019ef121-68fe-7b9c-946e-6ab4c586a2bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NaturalGasLiquidsReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_OilGasAndNaturalGasLiquidsGrossMember_019ef121-68fe-70de-abd5-8887c6019013" xlink:to="loc_srt_NaturalGasLiquidsReservesMember_019ef121-68fe-7b9c-946e-6ab4c586a2bb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NaturalGasGatheringTransportationMarketingAndProcessingMember_019ef121-68fe-737e-8562-9638c2ea0245" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NaturalGasGatheringTransportationMarketingAndProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68fe-77b2-aac5-c1b87a94f1fe" xlink:to="loc_us-gaap_NaturalGasGatheringTransportationMarketingAndProcessingMember_019ef121-68fe-737e-8562-9638c2ea0245" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019ef121-68fe-7612-84e5-30bb89b96a04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef121-68fe-7c42-b420-14a6d3e19ee3" xlink:to="loc_us-gaap_Revenues_019ef121-68fe-7612-84e5-30bb89b96a04" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresNarrativeDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresNarrativeDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-7d19-9d75-1cdfba7cd73b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-7d19-9d75-1cdfba7cd73b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7d19-9d75-1cdfba7cd73b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-7d19-9d75-1cdfba7cd73b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7d19-9d75-1cdfba7cd73b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7c4a-98bd-4d16e27e21fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-7d19-9d75-1cdfba7cd73b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7c4a-98bd-4d16e27e21fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_IKAVAcquisitionMember_019f1278-037f-7b7e-bc1d-f5fff8c0a132" xlink:href="mnr-20260630.xsd#mnr_IKAVAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7c4a-98bd-4d16e27e21fa" xlink:to="loc_mnr_IKAVAcquisitionMember_019f1278-037f-7b7e-bc1d-f5fff8c0a132" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_019f1278-037f-7733-b61e-78becece3f0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:to="loc_us-gaap_AssetAcquisitionAxis_019f1278-037f-7733-b61e-78becece3f0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7733-b61e-78becece3f0a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-037f-7733-b61e-78becece3f0a" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7733-b61e-78becece3f0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7a9d-9f45-2e6d9499e9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-037f-7733-b61e-78becece3f0a" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7a9d-9f45-2e6d9499e9b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SabinalAcquisitionMember_019f1278-037f-7a0e-95c8-6f5268ce10db" xlink:href="mnr-20260630.xsd#mnr_SabinalAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7a9d-9f45-2e6d9499e9b6" xlink:to="loc_mnr_SabinalAcquisitionMember_019f1278-037f-7a0e-95c8-6f5268ce10db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_FlycatcherAcquisitionMember_019f1278-037f-77fd-94e1-ddf2021a070d" xlink:href="mnr-20260630.xsd#mnr_FlycatcherAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f1278-037f-7a9d-9f45-2e6d9499e9b6" xlink:to="loc_mnr_FlycatcherAcquisitionMember_019f1278-037f-77fd-94e1-ddf2021a070d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f1278-037f-7c90-bbb1-df71c244fe4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:to="loc_us-gaap_CreditFacilityAxis_019f1278-037f-7c90-bbb1-df71c244fe4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1278-037f-7c90-bbb1-df71c244fe4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f1278-037f-7c90-bbb1-df71c244fe4f" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1278-037f-7c90-bbb1-df71c244fe4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1278-037f-744f-89c3-fd4537188a82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f1278-037f-7c90-bbb1-df71c244fe4f" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1278-037f-744f-89c3-fd4537188a82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f1278-037f-7f25-a258-2206148e62d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f1278-037f-744f-89c3-fd4537188a82" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f1278-037f-7f25-a258-2206148e62d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f1278-037f-733f-8a26-860bf73f695e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f1278-037f-733f-8a26-860bf73f695e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1278-037f-733f-8a26-860bf73f695e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f1278-037f-733f-8a26-860bf73f695e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1278-037f-733f-8a26-860bf73f695e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1278-037f-738d-8995-d93f4aa9937f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f1278-037f-733f-8a26-860bf73f695e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1278-037f-738d-8995-d93f4aa9937f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_RevolvingCreditAgreementMember_019f1278-037f-7db2-a677-496b7069c9d0" xlink:href="mnr-20260630.xsd#mnr_RevolvingCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1278-037f-738d-8995-d93f4aa9937f" xlink:to="loc_mnr_RevolvingCreditAgreementMember_019f1278-037f-7db2-a677-496b7069c9d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f1278-037f-7527-832a-a60c9243524c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7cec-9e1f-774ac5d9bad3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f1278-037f-7527-832a-a60c9243524c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1278-037f-7527-832a-a60c9243524c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f1278-037f-7527-832a-a60c9243524c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1278-037f-7527-832a-a60c9243524c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1278-037f-7c96-9a24-b5391547726d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f1278-037f-7527-832a-a60c9243524c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1278-037f-7c96-9a24-b5391547726d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f1278-037f-7632-9a76-799d4041199c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f1278-037f-7c96-9a24-b5391547726d" xlink:to="loc_us-gaap_LineOfCreditMember_019f1278-037f-7632-9a76-799d4041199c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019f1278-037f-7519-9a68-1a5c3278c31f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019f1278-037f-7519-9a68-1a5c3278c31f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-037f-7112-9b54-59b92d6c21d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-037f-7112-9b54-59b92d6c21d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-037f-7353-acb3-0ffc2b9c96df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-037f-7353-acb3-0ffc2b9c96df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f1278-037f-7851-9490-e4bf76dffa63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f1278-037f-7851-9490-e4bf76dffa63" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled_019f1278-037f-7440-a7b2-ef84eaddca9f" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_mnr_BusinessCombinationConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled_019f1278-037f-7440-a7b2-ef84eaddca9f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f1278-037f-7d40-9d73-96a3e059d3f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f1278-037f-7d40-9d73-96a3e059d3f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_019f1278-037f-7385-9ca1-d33f87c3faef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_019f1278-037f-7385-9ca1-d33f87c3faef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_019f1278-037f-7a53-bf0d-a782c08d42cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_019f1278-037f-7a53-bf0d-a782c08d42cb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_019f1278-037f-76bd-8c13-62726eef6efa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_019f1278-037f-76bd-8c13-62726eef6efa" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationAcquisitionRelatedCostExpenseGeneralAndAdministrativeExpenseReversal_019f1278-037f-7ae6-aaee-617214bd7aef" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationAcquisitionRelatedCostExpenseGeneralAndAdministrativeExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_mnr_BusinessCombinationAcquisitionRelatedCostExpenseGeneralAndAdministrativeExpenseReversal_019f1278-037f-7ae6-aaee-617214bd7aef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-037f-72ed-bab8-2eecc0725e54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-037f-72ed-bab8-2eecc0725e54" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-037f-75c5-904c-74d0d8d5388f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-037f-75c5-904c-74d0d8d5388f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsTransferred_019f1278-037f-7867-a63a-07c95d4929ec" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsTransferred_019f1278-037f-7867-a63a-07c95d4929ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled_019f1278-037f-7317-a325-690edc07a3a8" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableUnitsCancelled_019f1278-037f-7317-a325-690edc07a3a8" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f1278-037f-7cfe-9f8c-8ce4cd810317" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f1278-037f-7cfe-9f8c-8ce4cd810317" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_019f1278-037f-7666-9e81-cc38c162aec7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-75d6-ad72-82281a570c6b" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_019f1278-037f-7666-9e81-cc38c162aec7" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofIKAVAcquisitionDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresScheduleofIKAVAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofIKAVAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7945-91e9-db825c7f9917" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7945-91e9-db825c7f9917" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-78c0-afba-1a1196b62157" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-037f-7945-91e9-db825c7f9917" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-78c0-afba-1a1196b62157" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-78c0-afba-1a1196b62157_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-78c0-afba-1a1196b62157" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-78c0-afba-1a1196b62157_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7db7-8d90-f731fb5c5fa2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-037f-78c0-afba-1a1196b62157" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7db7-8d90-f731fb5c5fa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_IKAVAcquisitionMember_019f1278-037f-7c11-9fc5-ef9db6e8facb" xlink:href="mnr-20260630.xsd#mnr_IKAVAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-037f-7db7-8d90-f731fb5c5fa2" xlink:to="loc_mnr_IKAVAcquisitionMember_019f1278-037f-7c11-9fc5-ef9db6e8facb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f1278-037f-786e-b9ea-d3f42e6df9cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f1278-037f-786e-b9ea-d3f42e6df9cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_019f1278-037f-7437-9eeb-15f648b393d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_019f1278-037f-7437-9eeb-15f648b393d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f1278-037f-7063-b379-4c85ccd884d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f1278-037f-7063-b379-4c85ccd884d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-037f-709a-bfc2-d35e1a160584" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-037f-709a-bfc2-d35e1a160584" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-037f-718d-8789-47977c2472a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-037f-7281-87b5-6f68208945a7" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-037f-718d-8789-47977c2472a2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties_019f1278-037f-75c0-8763-9b1c2cce3eca" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties_019f1278-037f-75c0-8763-9b1c2cce3eca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccountsReceivable_019f1278-037f-73f6-8147-4e9aec171aed" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccountsReceivable_019f1278-037f-73f6-8147-4e9aec171aed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermDerivativeAssets_019f1278-037f-7535-9cee-65cf3873ddba" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermDerivativeAssets_019f1278-037f-7535-9cee-65cf3873ddba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_019f1278-037f-7fec-8c28-3d047bbd355e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_019f1278-037f-7fec-8c28-3d047bbd355e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019f1278-037f-7888-81fb-66a19ec63208" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019f1278-037f-7888-81fb-66a19ec63208" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment_019f1278-037f-7c7e-a83f-083a69472ec3" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment_019f1278-037f-7c7e-a83f-083a69472ec3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f1278-037f-7cf8-ada4-749752e41618" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f1278-037f-7cf8-ada4-749752e41618" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f1278-037f-7197-b99f-10fd5dd8638c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-037f-7213-871c-e28f6dfbbe4c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f1278-037f-7197-b99f-10fd5dd8638c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOutstandingChecksInExcessOfBankBalance_019f1278-037f-7622-be07-9c3735e5c7eb" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOutstandingChecksInExcessOfBankBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOutstandingChecksInExcessOfBankBalance_019f1278-037f-7622-be07-9c3735e5c7eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019f1278-037f-77ca-8838-ed4d171eda95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019f1278-037f-77ca-8838-ed4d171eda95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable_019f1278-037f-7fd4-bc82-b14ce0c6f202" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable_019f1278-037f-7fd4-bc82-b14ce0c6f202" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_019f1278-037f-79e6-b0f3-30d9cbc1e125" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_019f1278-037f-79e6-b0f3-30d9cbc1e125" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations_019f1278-037f-760c-b6ed-03d197f045a9" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations_019f1278-037f-760c-b6ed-03d197f045a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNonCurrentLiabilitiesDerivativeLiabilities_019f1278-037f-71e1-9bb8-3f26e7bbdb7e" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNonCurrentLiabilitiesDerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNonCurrentLiabilitiesDerivativeLiabilities_019f1278-037f-71e1-9bb8-3f26e7bbdb7e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019f1278-037f-7b8f-af25-541b207bbfbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019f1278-037f-7b8f-af25-541b207bbfbe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f1278-037f-7b3b-8fcc-88af263768a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-037f-71eb-b741-ac7a82a0c846" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f1278-037f-7b3b-8fcc-88af263768a4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-037f-79ad-840f-ae05936b0bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-037f-79ad-840f-ae05936b0bd3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-037f-71b5-b1ac-a15d536aa50f" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:to="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestShareIssuedNumberOfShares_019f1278-037f-7f35-903a-018424c623f7" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestShareIssuedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestShareIssuedNumberOfShares_019f1278-037f-7f35-903a-018424c623f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPricePerShare_019f1278-037f-77ca-811e-0f76dfce7452" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPricePerShare_019f1278-037f-77ca-811e-0f76dfce7452" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterests_019f1278-037f-7286-b8b7-930b596316b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterests_019f1278-037f-7286-b8b7-930b596316b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration_019f1278-037f-7f95-9c47-49d2d184ffaa" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration_019f1278-037f-7f95-9c47-49d2d184ffaa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019f1278-037f-7ba6-97fc-de4a9f4c89c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-037f-7507-a013-99b406016ded" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019f1278-037f-7ba6-97fc-de4a9f4c89c9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:to="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties_019f1278-037f-773b-843c-3d78a60a3432" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties_019f1278-037f-773b-843c-3d78a60a3432" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_019f1278-037f-7e7c-a051-d5e6d8de2436" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_019f1278-037f-7e7c-a051-d5e6d8de2436" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets_019f1278-037f-7610-8942-e84d4e75ad96" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets_019f1278-037f-7610-8942-e84d4e75ad96" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory_019f1278-037f-7b03-ab2a-26448c61dcc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory_019f1278-037f-7b03-ab2a-26448c61dcc2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_019f1278-037f-75a6-91c6-16cf02236043" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_019f1278-037f-75a6-91c6-16cf02236043" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment_019f1278-037f-7f1d-a88c-d8ee3371ff8b" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment_019f1278-037f-7f1d-a88c-d8ee3371ff8b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_019f1278-037f-75ad-8b6a-463899757f5c" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_019f1278-037f-75ad-8b6a-463899757f5c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-037f-78d1-bccd-5048291bb27c" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-037f-7b11-a78e-b476850d0a81" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-037f-78d1-bccd-5048291bb27c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:to="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOutstandingChecksInExcessOfBankBalance_019f1278-037f-7fb2-afca-336bf557d0a0" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOutstandingChecksInExcessOfBankBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOutstandingChecksInExcessOfBankBalance_019f1278-037f-7fb2-afca-336bf557d0a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayableAndAccruedLiabilities_019f1278-037f-7a9b-b92e-8ca7a6f8a1f1" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayableAndAccruedLiabilities_019f1278-037f-7a9b-b92e-8ca7a6f8a1f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-037f-74f9-a090-08c4aa9ab18d" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-037f-74f9-a090-08c4aa9ab18d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities_019f1278-037f-75d8-9698-de42012a042c" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities_019f1278-037f-75d8-9698-de42012a042c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-037f-7c1f-9ae4-70f7695ea00a" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-037f-7c1f-9ae4-70f7695ea00a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeLiabilities_019f1278-037f-7ef7-a94d-29539aa07d56" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeLiabilities_019f1278-037f-7ef7-a94d-29539aa07d56" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities_019f1278-037f-7e61-b93d-50b59278eb93" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities_019f1278-037f-7e61-b93d-50b59278eb93" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-037f-729f-bb16-6360b2a8db46" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-037f-7a88-84b8-2aad0b70e7aa" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-037f-729f-bb16-6360b2a8db46" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetAssetsAcquired_019f1278-037f-7651-b9f5-8224c59f57ac" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-037f-74e9-ac87-2e5b321fd177" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetAssetsAcquired_019f1278-037f-7651-b9f5-8224c59f57ac" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofSabinalAcquisitionDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresScheduleofSabinalAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofSabinalAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-771d-877c-edc4b8c406aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-771d-877c-edc4b8c406aa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-7233-b3c8-ebeb5c6fc854" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-771d-877c-edc4b8c406aa" xlink:to="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-7233-b3c8-ebeb5c6fc854" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7233-b3c8-ebeb5c6fc854_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-7233-b3c8-ebeb5c6fc854" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7233-b3c8-ebeb5c6fc854_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7ecc-96b9-563746fe4b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-7233-b3c8-ebeb5c6fc854" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7ecc-96b9-563746fe4b8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SabinalAcquisitionMember_019f1278-0380-78d8-b7b3-dcd8fef64300" xlink:href="mnr-20260630.xsd#mnr_SabinalAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7ecc-96b9-563746fe4b8b" xlink:to="loc_mnr_SabinalAcquisitionMember_019f1278-0380-78d8-b7b3-dcd8fef64300" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableNumberOfShares_019f1278-0380-790b-8fdb-31ebca95d77e" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableNumberOfShares_019f1278-0380-790b-8fdb-31ebca95d77e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionPricePerShare_019f1278-0380-70ed-bc23-95f7b9bc56ee" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_mnr_AssetAcquisitionPricePerShare_019f1278-0380-70ed-bc23-95f7b9bc56ee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f1278-0380-7a7a-9895-cb4a4dda2ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f1278-0380-7a7a-9895-cb4a4dda2ccd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-0380-73ea-9cb0-75a2f5dabe22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-0380-73ea-9cb0-75a2f5dabe22" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_019f1278-0380-74a0-af8b-f5e08250c43a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_019f1278-0380-74a0-af8b-f5e08250c43a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables_019f1278-0380-70cd-a1af-37099e05fa72" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables_019f1278-0380-70cd-a1af-37099e05fa72" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-0380-77c1-8d2f-8d6ea3811261" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-76c3-bac6-2a46edec42b9" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-0380-77c1-8d2f-8d6ea3811261" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-7319-a7ed-759acd46d311" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-7319-a7ed-759acd46d311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAccountsReceivableJointInterest_019f1278-0380-7d20-9901-36d9f454fa61" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAccountsReceivableJointInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionAccountsReceivableJointInterest_019f1278-0380-7d20-9901-36d9f454fa61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionInventories_019f1278-0380-77a2-8d4f-ed304f842453" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionInventories_019f1278-0380-77a2-8d4f-ed304f842453" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionOtherPropertyPlantAndEquipment_019f1278-0380-79e5-bc6a-42f1e747f759" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionOtherPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionOtherPropertyPlantAndEquipment_019f1278-0380-79e5-bc6a-42f1e747f759" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsOther_019f1278-0380-7103-9b14-3984b2439d68" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionAssetsOther_019f1278-0380-7103-9b14-3984b2439d68" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionShortTermDerivativeAssets_019f1278-0380-7c02-a98e-527e3704e747" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionShortTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionShortTermDerivativeAssets_019f1278-0380-7c02-a98e-527e3704e747" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionLongTermDerivativeAssets_019f1278-0380-7cb7-a395-25db238f79a1" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionLongTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionLongTermDerivativeAssets_019f1278-0380-7cb7-a395-25db238f79a1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquired_019f1278-0380-73e6-9590-e10c7a2d637d" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-77d1-aa3f-281c931ae5ce" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquired_019f1278-0380-73e6-9590-e10c7a2d637d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAccruedLiabilities_019f1278-0380-7c09-9733-196a4acdf2ce" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:to="loc_mnr_AssetAcquisitionAccruedLiabilities_019f1278-0380-7c09-9733-196a4acdf2ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionRevenuePayable_019f1278-0380-7377-8903-fa66200fbbc5" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:to="loc_mnr_AssetAcquisitionRevenuePayable_019f1278-0380-7377-8903-fa66200fbbc5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_019f1278-0380-73c2-9862-34801ab6f2c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:to="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_019f1278-0380-73c2-9862-34801ab6f2c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionLiabilitiesAssumed_019f1278-0380-7ec3-b1b8-adf5219e47ef" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-71a0-a15d-833ebb1b8071" xlink:to="loc_mnr_AssetAcquisitionLiabilitiesAssumed_019f1278-0380-7ec3-b1b8-adf5219e47ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7a67-bcfe-d8fb3e520503" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7a67-bcfe-d8fb3e520503" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-71c5-9d99-d0ae0220b207" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:to="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestIssuedAndIssuableNumberOfShares_019f1278-0380-71f0-a9e4-ef34e82d02ed" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestIssuedAndIssuableNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityInterestIssuedAndIssuableNumberOfShares_019f1278-0380-71f0-a9e4-ef34e82d02ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetAcquisitionPricePerShare_019f1278-0380-719e-8cf9-cf3add70c73e" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetAcquisitionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetAcquisitionPricePerShare_019f1278-0380-719e-8cf9-cf3add70c73e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityConsideration_019f1278-0380-76f5-a264-97ad39e43684" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentEquityConsideration_019f1278-0380-76f5-a264-97ad39e43684" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration_019f1278-0380-766e-b20e-b77445fe7a68" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCashConsideration_019f1278-0380-766e-b20e-b77445fe7a68" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCapitalizedTransactionCosts_019f1278-0380-777f-aede-9f488ee47eea" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCapitalizedTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentCapitalizedTransactionCosts_019f1278-0380-777f-aede-9f488ee47eea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables_019f1278-0380-7c22-b094-959ecc80c426" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables_019f1278-0380-7c22-b094-959ecc80c426" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsideration_019f1278-0380-7a61-b7a4-dab6d945818d" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7888-8f99-28a3a75e42ee" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsideration_019f1278-0380-7a61-b7a4-dab6d945818d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-70b3-9352-908d638d692f" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOilAndGasPropertyFullCostMethodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-70b3-9352-908d638d692f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest_019f1278-0380-715e-b5ee-1721d2beb0f0" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest_019f1278-0380-715e-b5ee-1721d2beb0f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentInventories_019f1278-0380-712d-b511-b23b25f8519a" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentInventories_019f1278-0380-712d-b511-b23b25f8519a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyPlantAndEquipment_019f1278-0380-7bc5-82f0-c360a8ce530b" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyPlantAndEquipment_019f1278-0380-7bc5-82f0-c360a8ce530b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsOther_019f1278-0380-7df2-9153-11f5582bdccd" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsOther_019f1278-0380-7df2-9153-11f5582bdccd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets_019f1278-0380-7ef0-95d6-9e7b2e71c109" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentShortTermDerivativeAssets_019f1278-0380-7ef0-95d6-9e7b2e71c109" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeAssets_019f1278-0380-7754-a90a-9aecb8196778" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDerivativeAssets_019f1278-0380-7754-a90a-9aecb8196778" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-0380-77fa-8f1a-a20c557a5057" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAdjustmentsAbstract_019f1278-0380-7dba-ad76-a55d321af5e8" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-0380-77fa-8f1a-a20c557a5057" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities_019f1278-0380-7a69-8d64-8327b133e313" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities_019f1278-0380-7a69-8d64-8327b133e313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-0380-7d36-8e06-a1954a3e78cf" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-0380-7d36-8e06-a1954a3e78cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-0380-7221-b131-79a227b84eac" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-0380-7221-b131-79a227b84eac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-0380-7eeb-ab4f-2a8d595165cd" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAdjustmentsAbstract_019f1278-0380-7da2-88ff-42c322400e1b" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-0380-7eeb-ab4f-2a8d595165cd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-77bb-826f-0c3971cce6a4" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-720b-ba74-a6a26ea2a59a" xlink:to="loc_mnr_AssetAcquisitionProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-77bb-826f-0c3971cce6a4" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofXTOAcquisitionDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresScheduleofXTOAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofXTOAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-79cb-9944-2aa09448dcfb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-79cb-9944-2aa09448dcfb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-793f-b481-8a85eaa624af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-79cb-9944-2aa09448dcfb" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-793f-b481-8a85eaa624af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-793f-b481-8a85eaa624af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-793f-b481-8a85eaa624af" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-793f-b481-8a85eaa624af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7c8c-8cdd-d01009b79ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-793f-b481-8a85eaa624af" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7c8c-8cdd-d01009b79ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_XTOAcquisitionMember_019f1278-0380-757d-b1ae-fd123a207682" xlink:href="mnr-20260630.xsd#mnr_XTOAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7c8c-8cdd-d01009b79ab1" xlink:to="loc_mnr_XTOAcquisitionMember_019f1278-0380-757d-b1ae-fd123a207682" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-0380-729a-8d8c-88a1c1543018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-0380-729a-8d8c-88a1c1543018" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-0380-7b46-aa49-652f68df46f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-0380-729a-8d8c-88a1c1543018" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019f1278-0380-7b46-aa49-652f68df46f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationPurchasePriceAdjustmentsReceivables_019f1278-0380-7fa1-8538-061a7a3ed2bc" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationPurchasePriceAdjustmentsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-0380-729a-8d8c-88a1c1543018" xlink:to="loc_mnr_BusinessCombinationPurchasePriceAdjustmentsReceivables_019f1278-0380-7fa1-8538-061a7a3ed2bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-0380-7137-aefe-1bacea448985" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_019f1278-0380-729a-8d8c-88a1c1543018" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019f1278-0380-7137-aefe-1bacea448985" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties_019f1278-0380-7552-b66b-4d0d9d9271e1" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:to="loc_mnr_BusinessCombinationRecognizedAssetAcquiredProvedOilAndNaturalGasProperties_019f1278-0380-7552-b66b-4d0d9d9271e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetAcquiredAccountsReceivableJointInterest_019f1278-0380-7ef9-b783-d731c369f875" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetAcquiredAccountsReceivableJointInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetAcquiredAccountsReceivableJointInterest_019f1278-0380-7ef9-b783-d731c369f875" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment_019f1278-0380-7777-8cc7-961d941235d6" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherPropertyAndEquipment_019f1278-0380-7777-8cc7-961d941235d6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f1278-0380-70f4-8611-29688aab4e65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f1278-0380-70f4-8611-29688aab4e65" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f1278-0380-78e9-862a-5f7e75fa28cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-7541-add4-27968dbe674b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_019f1278-0380-78e9-862a-5f7e75fa28cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable_019f1278-0380-758a-9953-2592f3a5d6b1" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRevenuePayable_019f1278-0380-758a-9953-2592f3a5d6b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedAccruedLiabilities_019f1278-0380-7c6c-aabb-2db181635348" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedLiabilityAssumedAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:to="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedAccruedLiabilities_019f1278-0380-7c6c-aabb-2db181635348" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations_019f1278-0380-7a3b-aeb7-ed5018190c06" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:to="loc_mnr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetRetirementObligations_019f1278-0380-7a3b-aeb7-ed5018190c06" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f1278-0380-7050-a033-ec2703d47773" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-75f9-87b8-13d1c117456f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f1278-0380-7050-a033-ec2703d47773" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-79c3-8743-b8668ecfc003" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-79c3-8743-b8668ecfc003" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-71ff-abd8-2657b977f7e5" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7b49-bd97-de308ccf723b" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:to="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7b49-bd97-de308ccf723b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPaymentsForAssetAcquisitions_019f1278-0380-7b89-b81e-f9a051eab8af" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPaymentsForAssetAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7b49-bd97-de308ccf723b" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPaymentsForAssetAcquisitions_019f1278-0380-7b89-b81e-f9a051eab8af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables_019f1278-0380-772b-8c71-a1f211c84131" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7b49-bd97-de308ccf723b" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAdjustmentsReceivables_019f1278-0380-772b-8c71-a1f211c84131" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019f1278-0380-759d-aca4-351eb0e61263" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationConsiderationTransferredAdjustmentsAbstract_019f1278-0380-7b49-bd97-de308ccf723b" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019f1278-0380-759d-aca4-351eb0e61263" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:to="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties_019f1278-0380-798d-a647-1a983b88eebc" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentProvedOilAndNaturalGasProperties_019f1278-0380-798d-a647-1a983b88eebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest_019f1278-0380-7239-ab95-8309dd7c23cd" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivableJointInterest_019f1278-0380-7239-ab95-8309dd7c23cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment_019f1278-0380-7e26-8c04-cbe5d08316d5" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherPropertyAndEquipment_019f1278-0380-7e26-8c04-cbe5d08316d5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_019f1278-0380-7b41-af06-531158e39fc6" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_019f1278-0380-7b41-af06-531158e39fc6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-0380-7ced-9e0c-c909e2cf9c41" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedAssetAcquiredAssetAdjustmentsAbstract_019f1278-0380-784c-ad2c-3aa70dd1243f" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquired_019f1278-0380-7ced-9e0c-c909e2cf9c41" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:to="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-0380-7765-8263-62342e12c4c9" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRevenuePayable_019f1278-0380-7765-8263-62342e12c4c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities_019f1278-0380-764e-b091-c20372414bd4" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedLiabilities_019f1278-0380-764e-b091-c20372414bd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-0380-75f9-982c-821cd3cc147a" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetRetirementObligations_019f1278-0380-75f9-982c-821cd3cc147a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-0380-7f48-95dc-f02a8a457386" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_BusinessCombinationRecognizedLiabilityAssumedLiabilityAdjustmentsAbstract_019f1278-0380-7ddd-b3f6-3fae86661473" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLiabilitiesAssumed_019f1278-0380-7f48-95dc-f02a8a457386" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7301-8478-8bccfb4a07d6" xlink:href="mnr-20260630.xsd#mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_019f1278-0380-7b24-b3cc-418dfca737d4" xlink:to="loc_mnr_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7301-8478-8bccfb4a07d6" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofFlycatcherAcquisitionDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresScheduleofFlycatcherAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofFlycatcherAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-7b66-a112-528d31195863" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:to="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-7b66-a112-528d31195863" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-75de-830c-f515b1e05ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AssetAcquisitionTable_019f1278-0380-7b66-a112-528d31195863" xlink:to="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-75de-830c-f515b1e05ed8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-75de-830c-f515b1e05ed8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-75de-830c-f515b1e05ed8" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-75de-830c-f515b1e05ed8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7e69-93e5-b82989126952" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f1278-0380-75de-830c-f515b1e05ed8" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7e69-93e5-b82989126952" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_FlycatcherAcquisitionMember_019f1278-0380-73c8-9492-dc4140e9b498" xlink:href="mnr-20260630.xsd#mnr_FlycatcherAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f1278-0380-7e69-93e5-b82989126952" xlink:to="loc_mnr_FlycatcherAcquisitionMember_019f1278-0380-73c8-9492-dc4140e9b498" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-0380-7e45-8061-d9ecc2b58b73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:to="loc_us-gaap_PaymentsToAcquireOilAndGasPropertyAndEquipment_019f1278-0380-7e45-8061-d9ecc2b58b73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_019f1278-0380-73c9-918a-edf69c00309c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_019f1278-0380-73c9-918a-edf69c00309c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables_019f128b-6c10-761b-90a5-749837d61030" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:to="loc_mnr_AssetAcquisitionPurchasePriceAdjustmentsReceivables_019f128b-6c10-761b-90a5-749837d61030" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-0380-7fa6-855c-c70058f8b164" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionConsiderationTransferredAbstract_019f1278-0380-728f-9fb6-2552ad8121c7" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019f1278-0380-7fa6-855c-c70058f8b164" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-73e5-921f-be0495b9231f" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-73e5-921f-be0495b9231f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-7b89-a8d1-6fbb47e1dc7c" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-73e5-921f-be0495b9231f" xlink:to="loc_mnr_AssetAcquisitionPropertyPlantAndEquipmentOilAndGasPropertyFullCostMethodNet_019f1278-0380-7b89-a8d1-6fbb47e1dc7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsOther_019f1278-0380-70e2-b22a-457f86b661ce" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-73e5-921f-be0495b9231f" xlink:to="loc_mnr_AssetAcquisitionAssetsOther_019f1278-0380-70e2-b22a-457f86b661ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquired_019f1278-0380-765f-93eb-69e22a88161d" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_019f1278-0380-73e5-921f-be0495b9231f" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquired_019f1278-0380-765f-93eb-69e22a88161d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-711f-9ff0-1210577773ee" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-711f-9ff0-1210577773ee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionRevenuePayable_019f1278-0380-7033-9231-d928bfebf6ea" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionRevenuePayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-711f-9ff0-1210577773ee" xlink:to="loc_mnr_AssetAcquisitionRevenuePayable_019f1278-0380-7033-9231-d928bfebf6ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_019f1278-0380-70ac-bc73-554374ead00d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-711f-9ff0-1210577773ee" xlink:to="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_019f1278-0380-70ac-bc73-554374ead00d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionLiabilitiesAssumed_019f1278-0380-7f74-a60c-369889cfc86c" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionLiabilitiesAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_019f1278-0380-711f-9ff0-1210577773ee" xlink:to="loc_mnr_AssetAcquisitionLiabilitiesAssumed_019f1278-0380-7f74-a60c-369889cfc86c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7a34-b583-294ec8a01d22" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019f1278-0380-77b5-9507-8e0b037024e8" xlink:to="loc_mnr_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet_019f1278-0380-7a34-b583-294ec8a01d22" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofProFormaConsolidatedFinancialInformationDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#AcquisitionsandDivestituresScheduleofProFormaConsolidatedFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/AcquisitionsandDivestituresScheduleofProFormaConsolidatedFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-72f5-93f5-f4fb89b7bf35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-7583-a300-76ad6784a40f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-72f5-93f5-f4fb89b7bf35" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-7583-a300-76ad6784a40f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-7b85-b506-28c88a2c90c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f1278-0380-7583-a300-76ad6784a40f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-7b85-b506-28c88a2c90c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7b85-b506-28c88a2c90c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-7b85-b506-28c88a2c90c7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7b85-b506-28c88a2c90c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7bbd-a30b-fbc1da173687" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f1278-0380-7b85-b506-28c88a2c90c7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7bbd-a30b-fbc1da173687" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_IKAVAndXTOAcquisitionMember_019fa2b7-a458-759a-a2bf-d99d9bd2d71c" xlink:href="mnr-20260630.xsd#mnr_IKAVAndXTOAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f1278-0380-7bbd-a30b-fbc1da173687" xlink:to="loc_mnr_IKAVAndXTOAcquisitionMember_019fa2b7-a458-759a-a2bf-d99d9bd2d71c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_019f1278-0380-7ec5-80d2-aadb0d1c2e83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-72f5-93f5-f4fb89b7bf35" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_019f1278-0380-7ec5-80d2-aadb0d1c2e83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_019f1278-0380-751a-b98d-ac8d689b7027" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f1278-0380-72f5-93f5-f4fb89b7bf35" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_019f1278-0380-751a-b98d-ac8d689b7027" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/PropertyandEquipmentDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#PropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/PropertyandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019ef121-68ff-7764-82fa-f8eee700900b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019ef121-68ff-7d8a-8d3c-93065a964b24" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019ef121-68ff-7764-82fa-f8eee700900b" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019ef121-68ff-7d8a-8d3c-93065a964b24" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019ef121-68ff-7f88-8a2f-9ed2397add1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019ef121-68ff-7d8a-8d3c-93065a964b24" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019ef121-68ff-7f88-8a2f-9ed2397add1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-7f88-8a2f-9ed2397add1b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019ef121-68ff-7f88-8a2f-9ed2397add1b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-7f88-8a2f-9ed2397add1b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019ef121-68ff-7f88-8a2f-9ed2397add1b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_GasGatheringEquipmentMember_019ef121-68ff-7bd7-8744-fc5f0ec39fa5" xlink:href="mnr-20260630.xsd#mnr_GasGatheringEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:to="loc_mnr_GasGatheringEquipmentMember_019ef121-68ff-7bd7-8744-fc5f0ec39fa5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_GasProcessingEquipmentMember_019ef121-68ff-7139-9771-25ad267e2b16" xlink:href="mnr-20260630.xsd#mnr_GasProcessingEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:to="loc_mnr_GasProcessingEquipmentMember_019ef121-68ff-7139-9771-25ad267e2b16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_WaterDisposalAssetsMember_019ef121-68ff-71f6-ae29-dbb9c1dbfd74" xlink:href="mnr-20260630.xsd#mnr_WaterDisposalAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:to="loc_mnr_WaterDisposalAssetsMember_019ef121-68ff-71f6-ae29-dbb9c1dbfd74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VehiclesMember_019f1238-6351-7185-b9b4-86e54559462f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:to="loc_us-gaap_VehiclesMember_019f1238-6351-7185-b9b4-86e54559462f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_019ef121-68ff-7a86-8be6-8c23e91fbaa7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019ef121-68ff-741b-aef0-dbaffe601526" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_019ef121-68ff-7a86-8be6-8c23e91fbaa7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-68ff-78f5-84dd-f31daf412a73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019ef121-68ff-7764-82fa-f8eee700900b" xlink:to="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-68ff-78f5-84dd-f31daf412a73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodGross_019ef121-68ff-7258-93db-a6312f7837ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-68ff-78f5-84dd-f31daf412a73" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodGross_019ef121-68ff-7258-93db-a6312f7837ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodDepletion_019f1239-23c3-78a0-9d2c-b46f1d1d6aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodDepletion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-68ff-78f5-84dd-f31daf412a73" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodDepletion_019f1239-23c3-78a0-9d2c-b46f1d1d6aa9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasPropertyFullCostMethodNet_019ef121-68ff-76fe-8426-c16382a36bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasPropertyFullCostMethodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OilAndGasPropertyAbstract_019ef121-68ff-78f5-84dd-f31daf412a73" xlink:to="loc_us-gaap_OilAndGasPropertyFullCostMethodNet_019ef121-68ff-76fe-8426-c16382a36bf1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-68ff-777b-83a9-c4f3a32594d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019ef121-68ff-7764-82fa-f8eee700900b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-68ff-777b-83a9-c4f3a32594d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019ef121-68ff-7706-896d-8828f457e486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-68ff-777b-83a9-c4f3a32594d2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019ef121-68ff-7706-896d-8828f457e486" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019ef121-68ff-79b9-9861-72e28de00728" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-68ff-777b-83a9-c4f3a32594d2" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019ef121-68ff-79b9-9861-72e28de00728" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019ef121-68ff-7aea-9e57-fdd617ac71a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNetAbstract_019ef121-68ff-777b-83a9-c4f3a32594d2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019ef121-68ff-7aea-9e57-fdd617ac71a1" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/LongTermDebtDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#LongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/LongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f177c-ac3c-7e5d-ad93-36a1883fcfc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:to="loc_us-gaap_CreditFacilityAxis_019f177c-ac3c-7e5d-ad93-36a1883fcfc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-7e5d-ad93-36a1883fcfc1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019f177c-ac3c-7e5d-ad93-36a1883fcfc1" xlink:to="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-7e5d-ad93-36a1883fcfc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-778e-aeb4-ae604be9e7b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019f177c-ac3c-7e5d-ad93-36a1883fcfc1" xlink:to="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-778e-aeb4-ae604be9e7b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f177c-ac3c-712d-ab4f-1a910b153b73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-778e-aeb4-ae604be9e7b6" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f177c-ac3c-712d-ab4f-1a910b153b73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019f177c-d234-7e9e-901e-ff9e9c8d8294" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f177c-ac3c-778e-aeb4-ae604be9e7b6" xlink:to="loc_us-gaap_SecuredDebtMember_019f177c-d234-7e9e-901e-ff9e9c8d8294" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f177c-ac3c-716a-bcc0-5e81928c687d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f177c-ac3c-716a-bcc0-5e81928c687d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-716a-bcc0-5e81928c687d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f177c-ac3c-716a-bcc0-5e81928c687d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-716a-bcc0-5e81928c687d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-7b3a-8aad-214d0d03abae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f177c-ac3c-716a-bcc0-5e81928c687d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-7b3a-8aad-214d0d03abae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_NewCreditAgreementMember_019f177c-ac3c-7e60-9b24-9819d3860e72" xlink:href="mnr-20260630.xsd#mnr_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-7b3a-8aad-214d0d03abae" xlink:to="loc_mnr_NewCreditAgreementMember_019f177c-ac3c-7e60-9b24-9819d3860e72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_TermLoanCreditAgreementMember_019f177c-d234-794e-a71e-ac46d666d065" xlink:href="mnr-20260630.xsd#mnr_TermLoanCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-7b3a-8aad-214d0d03abae" xlink:to="loc_mnr_TermLoanCreditAgreementMember_019f177c-d234-794e-a71e-ac46d666d065" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_RevolvingCreditAgreementMember_019f177c-d234-7df6-b14f-33644f2734d3" xlink:href="mnr-20260630.xsd#mnr_RevolvingCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f177c-ac3c-7b3a-8aad-214d0d03abae" xlink:to="loc_mnr_RevolvingCreditAgreementMember_019f177c-d234-7df6-b14f-33644f2734d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f177c-ac3c-7ebe-89fc-ba200cadc263" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f177c-ac3c-7ebe-89fc-ba200cadc263" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7ebe-89fc-ba200cadc263_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f177c-ac3c-7ebe-89fc-ba200cadc263" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7ebe-89fc-ba200cadc263_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7499-8f28-b547f6b73cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019f177c-ac3c-7ebe-89fc-ba200cadc263" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7499-8f28-b547f6b73cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f177c-ac3c-71b7-9bad-112f1ca2ed73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7499-8f28-b547f6b73cbc" xlink:to="loc_us-gaap_LineOfCreditMember_019f177c-ac3c-71b7-9bad-112f1ca2ed73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_TermLoansMember_019f177c-ac3c-79d2-84ab-13c260cf03f2" xlink:href="mnr-20260630.xsd#mnr_TermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f177c-ac3c-7499-8f28-b547f6b73cbc" xlink:to="loc_mnr_TermLoansMember_019f177c-ac3c-79d2-84ab-13c260cf03f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_019f177c-ac3c-7340-9115-a43a0df92438" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:to="loc_us-gaap_VariableRateAxis_019f177c-ac3c-7340-9115-a43a0df92438" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019f177c-ac3c-7340-9115-a43a0df92438_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_019f177c-ac3c-7340-9115-a43a0df92438" xlink:to="loc_us-gaap_VariableRateDomain_019f177c-ac3c-7340-9115-a43a0df92438_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_019f177c-ac3c-7340-9115-a43a0df92438" xlink:to="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_019f177c-ac3c-75f4-8891-f9712a541000" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_019f177c-ac3c-75f4-8891-f9712a541000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_019f177c-ac3c-71ce-8965-77be96e0cc1c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:to="loc_us-gaap_BaseRateMember_019f177c-ac3c-71ce-8965-77be96e0cc1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SecuredOvernightFinancingRateSOFROneMonthMember_019f177c-d234-79da-abc7-02230cbeda37" xlink:href="mnr-20260630.xsd#mnr_SecuredOvernightFinancingRateSOFROneMonthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:to="loc_mnr_SecuredOvernightFinancingRateSOFROneMonthMember_019f177c-d234-79da-abc7-02230cbeda37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SecuredOvernightFinancingRateSOFRTwoMonthMember_019f177c-d234-7dcd-bd9f-23e4964088f2" xlink:href="mnr-20260630.xsd#mnr_SecuredOvernightFinancingRateSOFRTwoMonthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:to="loc_mnr_SecuredOvernightFinancingRateSOFRTwoMonthMember_019f177c-d234-7dcd-bd9f-23e4964088f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SecuredOvernightFinancingRateSOFRThreeMonthMember_019f177c-d234-745a-99ad-76669e3ed078" xlink:href="mnr-20260630.xsd#mnr_SecuredOvernightFinancingRateSOFRThreeMonthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f177c-ac3c-72e0-8257-75af5a8a00a1" xlink:to="loc_mnr_SecuredOvernightFinancingRateSOFRThreeMonthMember_019f177c-d234-745a-99ad-76669e3ed078" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f177c-ac3c-7984-b43c-2a98a48bda2c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef121-68ff-7ec3-9580-686d748d205c" xlink:to="loc_srt_RangeAxis_019f177c-ac3c-7984-b43c-2a98a48bda2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f177c-ac3c-7984-b43c-2a98a48bda2c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f177c-ac3c-7984-b43c-2a98a48bda2c" xlink:to="loc_srt_RangeMember_019f177c-ac3c-7984-b43c-2a98a48bda2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f177c-ac3c-78e2-92b7-192efc82f181" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f177c-ac3c-7984-b43c-2a98a48bda2c" xlink:to="loc_srt_RangeMember_019f177c-ac3c-78e2-92b7-192efc82f181" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f177c-ac3c-7463-bb4c-9a36e6e86e26" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f177c-ac3c-78e2-92b7-192efc82f181" xlink:to="loc_srt_MinimumMember_019f177c-ac3c-7463-bb4c-9a36e6e86e26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f177c-ac3c-7239-9421-86cff3c38e33" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f177c-ac3c-78e2-92b7-192efc82f181" xlink:to="loc_srt_MaximumMember_019f177c-ac3c-7239-9421-86cff3c38e33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019f177c-ac3c-745d-9ffa-ecdeeeaf2142" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019f177c-ac3c-745d-9ffa-ecdeeeaf2142" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f177c-ac3c-7d62-8805-f6761839d53a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f177c-ac3c-7d62-8805-f6761839d53a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f177c-ac3c-76c6-a685-e4b00219378d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f177c-ac3c-76c6-a685-e4b00219378d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_019f177c-ac3c-7ad9-b590-be9fb70be491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_019f177c-ac3c-7ad9-b590-be9fb70be491" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_DebtInstrumentCovenantNetLeverageRatioMaximum_019f177c-ac3c-7788-b203-1f7998a91e47" xlink:href="mnr-20260630.xsd#mnr_DebtInstrumentCovenantNetLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_mnr_DebtInstrumentCovenantNetLeverageRatioMaximum_019f177c-ac3c-7788-b203-1f7998a91e47" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_DebtInstrumentCovenantCurrentRatioMinimum_019f177c-ac3c-785e-b54e-61a2c34ece37" xlink:href="mnr-20260630.xsd#mnr_DebtInstrumentCovenantCurrentRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_mnr_DebtInstrumentCovenantCurrentRatioMinimum_019f177c-ac3c-785e-b54e-61a2c34ece37" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_LineOfCreditFacilityAccordionFeatureIncreaseInBorrowingCapacity_019f177c-ac3c-7438-91a4-15ab6a6591c0" xlink:href="mnr-20260630.xsd#mnr_LineOfCreditFacilityAccordionFeatureIncreaseInBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_mnr_LineOfCreditFacilityAccordionFeatureIncreaseInBorrowingCapacity_019f177c-ac3c-7438-91a4-15ab6a6591c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019f177c-ac3c-7caf-926e-f95931296442" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019f177c-ac3c-7caf-926e-f95931296442" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_019fb65c-aa10-7740-a499-26e9e66493d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_019fb65c-aa10-7740-a499-26e9e66493d0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f177c-d234-71e1-bba3-878ff14ab2b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019f177c-d234-71e1-bba3-878ff14ab2b0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019f177c-d234-7352-a9d5-ca54cf10f3b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCredit_019f177c-d234-7352-a9d5-ca54cf10f3b8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019f177c-d234-73b0-9728-7d5598c1a6bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019f177c-d234-73b0-9728-7d5598c1a6bf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f177c-d234-74e5-a39f-d593d47e0a4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f177c-d234-74e5-a39f-d593d47e0a4d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_DebtInstrumentCreditSpreadOnVariableRate_019f177c-d234-7a54-b26a-30a140db742e" xlink:href="mnr-20260630.xsd#mnr_DebtInstrumentCreditSpreadOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_mnr_DebtInstrumentCreditSpreadOnVariableRate_019f177c-d234-7a54-b26a-30a140db742e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_DebtInstrumentVariableRateFloor_019f177c-d234-7192-bb95-88c1ce25b88b" xlink:href="mnr-20260630.xsd#mnr_DebtInstrumentVariableRateFloor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_mnr_DebtInstrumentVariableRateFloor_019f177c-d234-7192-bb95-88c1ce25b88b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f177c-d234-7d53-a98d-021ecefe1dc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019f177c-d234-7d53-a98d-021ecefe1dc4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019f177c-d234-7a1e-80f6-d1ad3e63e37b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019f177c-d234-7a1e-80f6-d1ad3e63e37b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019f177c-d234-70cd-b70b-1b5f5dd406cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019f177c-d234-70cd-b70b-1b5f5dd406cb" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_019f177c-d234-777e-8a98-557e197e42b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019f177c-ac3c-7e04-9fed-d13d3e2b261d" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_019f177c-d234-777e-8a98-557e197e42b4" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/DerivativeContractsScheduleofOpenFinancialDerivativePositionsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#DerivativeContractsScheduleofOpenFinancialDerivativePositionsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/DerivativeContractsScheduleofOpenFinancialDerivativePositionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AllExchangesAxis_019f1218-b3a8-7497-8120-c1bdc90ffd8b" xlink:href="mnr-20260630.xsd#mnr_AllExchangesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:to="loc_mnr_AllExchangesAxis_019f1218-b3a8-7497-8120-c1bdc90ffd8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AllExchangesDomain_019f1218-b3a8-7497-8120-c1bdc90ffd8b_default" xlink:href="mnr-20260630.xsd#mnr_AllExchangesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_mnr_AllExchangesAxis_019f1218-b3a8-7497-8120-c1bdc90ffd8b" xlink:to="loc_mnr_AllExchangesDomain_019f1218-b3a8-7497-8120-c1bdc90ffd8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AllExchangesDomain_019f1218-b3a8-7855-9f8f-2769cf3e1dbb" xlink:href="mnr-20260630.xsd#mnr_AllExchangesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_mnr_AllExchangesAxis_019f1218-b3a8-7497-8120-c1bdc90ffd8b" xlink:to="loc_mnr_AllExchangesDomain_019f1218-b3a8-7855-9f8f-2769cf3e1dbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_NYMEXWTIMember_019f1218-b3a8-79e1-a8bf-0d3a9e813e0a" xlink:href="mnr-20260630.xsd#mnr_NYMEXWTIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AllExchangesDomain_019f1218-b3a8-7855-9f8f-2769cf3e1dbb" xlink:to="loc_mnr_NYMEXWTIMember_019f1218-b3a8-79e1-a8bf-0d3a9e813e0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_NYMEXHHMember_019f1218-d183-7e7c-a8fe-e00eebda756d" xlink:href="mnr-20260630.xsd#mnr_NYMEXHHMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AllExchangesDomain_019f1218-b3a8-7855-9f8f-2769cf3e1dbb" xlink:to="loc_mnr_NYMEXHHMember_019f1218-d183-7e7c-a8fe-e00eebda756d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ArgusTMAMember_019f1219-1865-7c9d-b023-2e0977071cc7" xlink:href="mnr-20260630.xsd#mnr_ArgusTMAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_mnr_AllExchangesDomain_019f1218-b3a8-7855-9f8f-2769cf3e1dbb" xlink:to="loc_mnr_ArgusTMAMember_019f1219-1865-7c9d-b023-2e0977071cc7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_019f1218-b3a8-76b6-9197-c483df13d03f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:to="loc_srt_EnergyAxis_019f1218-b3a8-76b6-9197-c483df13d03f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019f1218-b3a8-76b6-9197-c483df13d03f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_019f1218-b3a8-76b6-9197-c483df13d03f" xlink:to="loc_srt_EnergyDomain_019f1218-b3a8-76b6-9197-c483df13d03f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019f1218-b3a8-7d22-9a2e-4c0065e70a65" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_019f1218-b3a8-76b6-9197-c483df13d03f" xlink:to="loc_srt_EnergyDomain_019f1218-b3a8-7d22-9a2e-4c0065e70a65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilMember_019f1218-b3a8-7d67-bb40-e8adcfe4296a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CrudeOilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019f1218-b3a8-7d22-9a2e-4c0065e70a65" xlink:to="loc_srt_CrudeOilMember_019f1218-b3a8-7d67-bb40-e8adcfe4296a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_019f1218-d183-7840-890b-196744d21921" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019f1218-b3a8-7d22-9a2e-4c0065e70a65" xlink:to="loc_srt_NaturalGasReservesMember_019f1218-d183-7840-890b-196744d21921" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1218-b3a8-7d79-abf1-361dbee4d8e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1218-b3a8-7d79-abf1-361dbee4d8e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-7d79-abf1-361dbee4d8e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1218-b3a8-7d79-abf1-361dbee4d8e4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-7d79-abf1-361dbee4d8e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1218-b3a8-7d79-abf1-361dbee4d8e4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CommodityContractPeriodRemainderOfFiscalYearMember_019f1218-b3a8-7550-b977-f5a9c25e75ec" xlink:href="mnr-20260630.xsd#mnr_CommodityContractPeriodRemainderOfFiscalYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:to="loc_mnr_CommodityContractPeriodRemainderOfFiscalYearMember_019f1218-b3a8-7550-b977-f5a9c25e75ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CommodityContractPeriodOneMember_019f1218-b3a8-738e-830d-d326bfdf48e4" xlink:href="mnr-20260630.xsd#mnr_CommodityContractPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:to="loc_mnr_CommodityContractPeriodOneMember_019f1218-b3a8-738e-830d-d326bfdf48e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CommodityContractPeriodTwoMember_019f1218-b3a8-7831-b2dd-d1aa9bfaad42" xlink:href="mnr-20260630.xsd#mnr_CommodityContractPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:to="loc_mnr_CommodityContractPeriodTwoMember_019f1218-b3a8-7831-b2dd-d1aa9bfaad42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CommodityContractPeriodThreeMember_019f1218-d183-7550-b126-16ed4d4c496b" xlink:href="mnr-20260630.xsd#mnr_CommodityContractPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1218-b3a8-76c7-a665-6dfc7f77b317" xlink:to="loc_mnr_CommodityContractPeriodThreeMember_019f1218-d183-7550-b126-16ed4d4c496b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019f1218-b3a8-7858-a120-be1420123230" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019f1218-b3a8-77fa-9021-2674b5dec659" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019f1218-b3a8-7858-a120-be1420123230" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-7858-a120-be1420123230_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019f1218-b3a8-7858-a120-be1420123230" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-7858-a120-be1420123230_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-77d9-83a1-a9ae2f61aff3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019f1218-b3a8-7858-a120-be1420123230" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-77d9-83a1-a9ae2f61aff3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SwapMember_019f1218-b3a8-7934-8f11-3d141caf0bbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-77d9-83a1-a9ae2f61aff3" xlink:to="loc_us-gaap_SwapMember_019f1218-b3a8-7934-8f11-3d141caf0bbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_CollarMember_019f1218-f681-7760-942f-561ec1e85b29" xlink:href="mnr-20260630.xsd#mnr_CollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f1218-b3a8-77d9-83a1-a9ae2f61aff3" xlink:to="loc_mnr_CollarMember_019f1218-f681-7760-942f-561ec1e85b29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_019f1218-b3a8-7d73-845d-9d4e4579e9fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_019f1218-b3a8-7d73-845d-9d4e4579e9fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeSwapTypeAverageFixedPrice_019f1218-b3a8-7494-aab3-37954ae050c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeSwapTypeAverageFixedPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeSwapTypeAverageFixedPrice_019f1218-b3a8-7494-aab3-37954ae050c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019f1218-d183-7720-b87e-92f4fae90e20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_019f1218-d183-7720-b87e-92f4fae90e20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFloorPrice_019f1218-f681-7361-bf44-c4d58e606807" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAverageFloorPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeAverageFloorPrice_019f1218-f681-7361-bf44-c4d58e606807" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageCapPrice_019f1218-f681-763a-972d-a86d2ad96b09" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAverageCapPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019f1218-b3a8-7c9a-bfc3-045953b985ce" xlink:to="loc_us-gaap_DerivativeAverageCapPrice_019f1218-f681-763a-972d-a86d2ad96b09" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019ef121-68ff-70bb-8d81-f9e1a26029ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_DerivativeTable_019ef121-68ff-70bb-8d81-f9e1a26029ef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019ef121-68ff-7294-9154-5d6c768f5c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019ef121-68ff-70bb-8d81-f9e1a26029ef" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019ef121-68ff-7294-9154-5d6c768f5c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019ef121-68ff-7ad6-bd41-37dc3021ace9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019ef121-68ff-7ad6-bd41-37dc3021ace9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019ef121-68ff-7d9c-b0d3-962905d35847" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019ef121-68ff-7d9c-b0d3-962905d35847" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7d73-bae1-27a23d2e04c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7d73-bae1-27a23d2e04c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019ef121-68ff-7ac5-8863-e2fb505bd006" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019ef121-68ff-7ac5-8863-e2fb505bd006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019ef121-68ff-7dbd-9f0f-a3f2758277d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019ef121-68ff-7dbd-9f0f-a3f2758277d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7e34-9e89-4e4db5330986" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7e34-9e89-4e4db5330986" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails_1" xlink:type="simple" xlink:href="mnr-20260630.xsd#DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails_1"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/DerivativeContractsScheduleofGrossAmountsofRecognizedDerivativeSubjecttoMasterNettingArrangementsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019ef121-68ff-70bb-8d81-f9e1a26029ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_DerivativeTable_019ef121-68ff-70bb-8d81-f9e1a26029ef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019ef121-68ff-7ad6-bd41-37dc3021ace9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019ef121-68ff-7ad6-bd41-37dc3021ace9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019ef121-68ff-7d9c-b0d3-962905d35847" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019ef121-68ff-7d9c-b0d3-962905d35847" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7d73-bae1-27a23d2e04c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_019ef121-68ff-7f37-9a05-e6bcaa0783c3" xlink:to="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7d73-bae1-27a23d2e04c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OffsettingDerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef121-68ff-7fa5-be4f-315f304d4691" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019ef121-68ff-7ac5-8863-e2fb505bd006" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019ef121-68ff-7ac5-8863-e2fb505bd006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019ef121-68ff-7dbd-9f0f-a3f2758277d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019ef121-68ff-7dbd-9f0f-a3f2758277d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7e34-9e89-4e4db5330986" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_019ef121-68ff-777e-9ff7-d9799d0b64f0" xlink:to="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019ef121-68ff-7e34-9e89-4e4db5330986" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/DerivativeContractsScheduleofGainsandLossesonDerivativesDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#DerivativeContractsScheduleofGainsandLossesonDerivativesDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/DerivativeContractsScheduleofGainsandLossesonDerivativesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019ef121-68ff-7f98-8511-0b738cf4dac2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019ef121-68ff-76a9-b06c-fe8ffd3a7fde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019ef121-68ff-7f98-8511-0b738cf4dac2" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019ef121-68ff-76a9-b06c-fe8ffd3a7fde" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_019ef121-68ff-744e-b6e8-9307f1868d6b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019ef121-68ff-76a9-b06c-fe8ffd3a7fde" xlink:to="loc_srt_EnergyAxis_019ef121-68ff-744e-b6e8-9307f1868d6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019ef121-68ff-744e-b6e8-9307f1868d6b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_019ef121-68ff-744e-b6e8-9307f1868d6b" xlink:to="loc_srt_EnergyDomain_019ef121-68ff-744e-b6e8-9307f1868d6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019ef121-68ff-7f84-81ce-18009099d343" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_019ef121-68ff-744e-b6e8-9307f1868d6b" xlink:to="loc_srt_EnergyDomain_019ef121-68ff-7f84-81ce-18009099d343" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilMember_019ef121-68ff-75b6-8a84-8ef8193b1450" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CrudeOilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019ef121-68ff-7f84-81ce-18009099d343" xlink:to="loc_srt_CrudeOilMember_019ef121-68ff-75b6-8a84-8ef8193b1450" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_019ef121-68ff-76ae-83f2-ac324e80d325" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019ef121-68ff-7f84-81ce-18009099d343" xlink:to="loc_srt_NaturalGasReservesMember_019ef121-68ff-76ae-83f2-ac324e80d325" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfDerivatives_019ef121-68ff-7aeb-9d94-a06928750fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019ef121-68ff-7f98-8511-0b738cf4dac2" xlink:to="loc_us-gaap_GainLossOnSaleOfDerivatives_019ef121-68ff-7aeb-9d94-a06928750fbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_019ef121-68ff-78aa-ae2f-a968ea2ccf0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019ef121-68ff-7f98-8511-0b738cf4dac2" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_019ef121-68ff-78aa-ae2f-a968ea2ccf0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019ef121-68ff-7fe8-a880-9fa3a1f87e19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019ef121-68ff-7f98-8511-0b738cf4dac2" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019ef121-68ff-7fe8-a880-9fa3a1f87e19" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef121-68ff-737a-98fa-7a57f5448adf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef121-68ff-7909-81fa-a7ab692e280f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef121-68ff-737a-98fa-7a57f5448adf" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef121-68ff-7909-81fa-a7ab692e280f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef121-68ff-7129-b9d3-b852e51f09c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef121-68ff-7909-81fa-a7ab692e280f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef121-68ff-7129-b9d3-b852e51f09c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-7129-b9d3-b852e51f09c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef121-68ff-7129-b9d3-b852e51f09c5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-7129-b9d3-b852e51f09c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-766d-89db-64a364065ef4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef121-68ff-7129-b9d3-b852e51f09c5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-766d-89db-64a364065ef4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019ef121-68ff-757a-a4df-adf85eec3641" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-766d-89db-64a364065ef4" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019ef121-68ff-757a-a4df-adf85eec3641" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019ef121-68ff-75d5-9d88-792cb7e685bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-766d-89db-64a364065ef4" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019ef121-68ff-75d5-9d88-792cb7e685bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019ef121-68ff-7d80-a883-b99af42f22f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef121-68ff-766d-89db-64a364065ef4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019ef121-68ff-7d80-a883-b99af42f22f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsAbstract_019ef121-68ff-7fee-8ca8-a151f9d16837" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef121-68ff-737a-98fa-7a57f5448adf" xlink:to="loc_us-gaap_DerivativeAssetsAbstract_019ef121-68ff-7fee-8ca8-a151f9d16837" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019ef121-68ff-7091-90a0-f13c169f08be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_019ef121-68ff-7fee-8ca8-a151f9d16837" xlink:to="loc_us-gaap_DerivativeAssets_019ef121-68ff-7091-90a0-f13c169f08be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesAbstract_019ef121-68ff-724c-b7bd-1e46c86a7fab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef121-68ff-737a-98fa-7a57f5448adf" xlink:to="loc_us-gaap_DerivativeLiabilitiesAbstract_019ef121-68ff-724c-b7bd-1e46c86a7fab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019ef121-68ff-70b2-875b-8da33f6515c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_019ef121-68ff-724c-b7bd-1e46c86a7fab" xlink:to="loc_us-gaap_DerivativeLiabilities_019ef121-68ff-70b2-875b-8da33f6515c6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/EquityCompensationandDeferredCompensationPlanNarrativeDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#EquityCompensationandDeferredCompensationPlanNarrativeDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/EquityCompensationandDeferredCompensationPlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-75a0-82c0-7a2d90d4a385" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-75a0-82c0-7a2d90d4a385" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f11f1-ca6e-78a2-8df3-15b3e1642c09" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-75a0-82c0-7a2d90d4a385" xlink:to="loc_srt_RangeAxis_019f11f1-ca6e-78a2-8df3-15b3e1642c09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f11f1-ca6e-78a2-8df3-15b3e1642c09_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f11f1-ca6e-78a2-8df3-15b3e1642c09" xlink:to="loc_srt_RangeMember_019f11f1-ca6e-78a2-8df3-15b3e1642c09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f11f1-ca6e-796d-bf87-16c738d1d761" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f11f1-ca6e-78a2-8df3-15b3e1642c09" xlink:to="loc_srt_RangeMember_019f11f1-ca6e-796d-bf87-16c738d1d761" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f11f1-ca6e-771d-8130-a83e384239e7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f11f1-ca6e-796d-bf87-16c738d1d761" xlink:to="loc_srt_MinimumMember_019f11f1-ca6e-771d-8130-a83e384239e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f11f1-ef87-72e9-8346-7a3c7dfcd6a7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f11f1-ca6e-796d-bf87-16c738d1d761" xlink:to="loc_srt_MaximumMember_019f11f1-ef87-72e9-8346-7a3c7dfcd6a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f11f1-ca6e-7540-85f5-48994b6f53a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-75a0-82c0-7a2d90d4a385" xlink:to="loc_us-gaap_AwardTypeAxis_019f11f1-ca6e-7540-85f5-48994b6f53a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-7540-85f5-48994b6f53a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f11f1-ca6e-7540-85f5-48994b6f53a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-7540-85f5-48994b6f53a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f11f1-ca6e-7540-85f5-48994b6f53a7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ClassBIncentiveUnitsMember_019f11f1-ca6e-7843-b716-b4f34940a888" xlink:href="mnr-20260630.xsd#mnr_ClassBIncentiveUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:to="loc_mnr_ClassBIncentiveUnitsMember_019f11f1-ca6e-7843-b716-b4f34940a888" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PhantomShareUnitsPSUsTimeBasedMember_019f11f1-ca6e-792c-9696-eacb39f5fcb0" xlink:href="mnr-20260630.xsd#mnr_PhantomShareUnitsPSUsTimeBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:to="loc_mnr_PhantomShareUnitsPSUsTimeBasedMember_019f11f1-ca6e-792c-9696-eacb39f5fcb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_019f11f1-ef87-7acb-bdc8-38d945404186" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_019f11f1-ef87-7acb-bdc8-38d945404186" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_LongTermPerformanceUnitsMember_019f11f1-ef87-79c3-908e-4c12e684add4" xlink:href="mnr-20260630.xsd#mnr_LongTermPerformanceUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:to="loc_mnr_LongTermPerformanceUnitsMember_019f11f1-ef87-79c3-908e-4c12e684add4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShortTermPerformanceUnitsMember_019f11f1-ef87-7157-bb07-25b6452d0b3c" xlink:href="mnr-20260630.xsd#mnr_ShortTermPerformanceUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f11f1-ca6e-74b7-9897-d55f7e3fd118" xlink:to="loc_mnr_ShortTermPerformanceUnitsMember_019f11f1-ef87-7157-bb07-25b6452d0b3c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f11f2-0a56-7781-be1b-e3c0028eff5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-75a0-82c0-7a2d90d4a385" xlink:to="loc_us-gaap_PlanNameAxis_019f11f2-0a56-7781-be1b-e3c0028eff5b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f11f2-0a56-7781-be1b-e3c0028eff5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f11f2-0a56-7781-be1b-e3c0028eff5b" xlink:to="loc_us-gaap_PlanNameDomain_019f11f2-0a56-7781-be1b-e3c0028eff5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f11f2-0a56-73cc-94ac-831768f77fc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f11f2-0a56-7781-be1b-e3c0028eff5b" xlink:to="loc_us-gaap_PlanNameDomain_019f11f2-0a56-73cc-94ac-831768f77fc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_LongTermIncentivePlanMember_019f11f2-0a56-7fba-87a3-26d30e96ba58" xlink:href="mnr-20260630.xsd#mnr_LongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f11f2-0a56-73cc-94ac-831768f77fc2" xlink:to="loc_mnr_LongTermIncentivePlanMember_019f11f2-0a56-7fba-87a3-26d30e96ba58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f11f1-ca6e-73e1-9ff0-21a310ee2ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f11f1-ca6e-73e1-9ff0-21a310ee2ccb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardConversionUnitUponVesting_019f11f1-ca6e-7a84-9221-1f1fd8443169" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardConversionUnitUponVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardConversionUnitUponVesting_019f11f1-ca6e-7a84-9221-1f1fd8443169" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019f11f1-ef87-7b88-9066-17775e3e2a12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_ShareBasedCompensation_019f11f1-ef87-7b88-9066-17775e3e2a12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f11f1-ef87-7f8c-9e5b-dbe7c7342b89" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f11f1-ef87-7f8c-9e5b-dbe7c7342b89" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f11f1-ef87-7b0e-aa00-d1efe42e5229" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f11f1-ef87-7b0e-aa00-d1efe42e5229" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019f11f1-ef87-7663-8077-271934eb4322" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019f11f1-ef87-7663-8077-271934eb4322" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTargetPercentage_019f11f1-ef87-7ed5-ad56-993bce05ab49" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTargetPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTargetPercentage_019f11f1-ef87-7ed5-ad56-993bce05ab49" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardCategories_019f11f1-ef87-7306-a661-41a45f30f9e3" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardCategories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardCategories_019f11f1-ef87-7306-a661-41a45f30f9e3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriodForTranches_019f11f1-ef87-7cec-b221-dfa85e0d9dc0" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriodForTranches"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriodForTranches_019f11f1-ef87-7cec-b221-dfa85e0d9dc0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodOfReceiptOfVestedShares_019f11f1-ef87-7ace-8e11-05524449de76" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodOfReceiptOfVestedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodOfReceiptOfVestedShares_019f11f1-ef87-7ace-8e11-05524449de76" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f11f2-0a56-7abb-96c7-c8f3ec1d1a25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_019f11f2-0a56-7abb-96c7-c8f3ec1d1a25" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAutomaticIncreaseTerm_019f11f2-0a56-7199-bde9-f821af72e3fe" xlink:href="mnr-20260630.xsd#mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAutomaticIncreaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_mnr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAutomaticIncreaseTerm_019f11f2-0a56-7199-bde9-f821af72e3fe" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019f11f2-0a56-724f-82e1-ca3c5d1f5ffc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f11f1-ca6e-7636-b290-79536ce7ef35" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019f11f2-0a56-724f-82e1-ca3c5d1f5ffc" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/EquityCompensationandDeferredCompensationPlanScheduleofIncentiveUnitAwardsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#EquityCompensationandDeferredCompensationPlanScheduleofIncentiveUnitAwardsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/EquityCompensationandDeferredCompensationPlanScheduleofIncentiveUnitAwardsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-7106-a59a-b707374ce2b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-705f-9977-88a721fa183b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-7106-a59a-b707374ce2b9" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-705f-9977-88a721fa183b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7f4f-bbbb-2c669d27d313" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-705f-9977-88a721fa183b" xlink:to="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7f4f-bbbb-2c669d27d313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7f4f-bbbb-2c669d27d313_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7f4f-bbbb-2c669d27d313" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7f4f-bbbb-2c669d27d313_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-76dc-a381-697da99d8c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7f4f-bbbb-2c669d27d313" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-76dc-a381-697da99d8c7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PhantomShareUnitsPSUsTimeBasedMember_019ef121-68ff-7fb6-a726-b14ba3cb9d22" xlink:href="mnr-20260630.xsd#mnr_PhantomShareUnitsPSUsTimeBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-76dc-a381-697da99d8c7e" xlink:to="loc_mnr_PhantomShareUnitsPSUsTimeBasedMember_019ef121-68ff-7fb6-a726-b14ba3cb9d22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_019ef121-68ff-7bdd-a20d-3cfbc8eabb5e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-76dc-a381-697da99d8c7e" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_019ef121-68ff-7bdd-a20d-3cfbc8eabb5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-7106-a59a-b707374ce2b9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019ef121-68ff-7c95-8278-91af53701516" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019ef121-68ff-7c95-8278-91af53701516" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019ef121-68ff-7203-b66b-f6eee98aae26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019ef121-68ff-7203-b66b-f6eee98aae26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019ef121-68ff-7766-a56e-a607ea30e58c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019ef121-68ff-7766-a56e-a607ea30e58c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019ef121-68ff-78ce-a84a-902665bfdd70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019ef121-68ff-7a6b-b154-ff823c1e7810" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019ef121-68ff-78ce-a84a-902665bfdd70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019ef121-68ff-7fef-9259-67fa00ab2504" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-7106-a59a-b707374ce2b9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019ef121-68ff-7edf-af4c-63102033f1c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019ef121-68ff-7edf-af4c-63102033f1c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019ef121-68ff-72d5-9876-0f03bbb9322e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019ef121-68ff-72d5-9876-0f03bbb9322e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019ef121-68ff-7585-ba93-5edc9672e92a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019ef121-68ff-7585-ba93-5edc9672e92a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019ef121-68ff-7021-9d5c-36c84ec88570" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019ef121-68ff-7cc1-a1e8-58638683e5a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019ef121-68ff-7021-9d5c-36c84ec88570" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019ef121-68ff-7320-bb7c-cd23a6f13f70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/EquityCompensationPlansScheduleofAssumptionsUsedinMonteCarloSimulationDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#EquityCompensationPlansScheduleofAssumptionsUsedinMonteCarloSimulationDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/EquityCompensationPlansScheduleofAssumptionsUsedinMonteCarloSimulationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-7b18-906e-5e35dd38f335" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-7b18-906e-5e35dd38f335" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7c37-adc0-dfd9b1bbd553" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019ef121-68ff-7b18-906e-5e35dd38f335" xlink:to="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7c37-adc0-dfd9b1bbd553" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7c37-adc0-dfd9b1bbd553_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7c37-adc0-dfd9b1bbd553" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7c37-adc0-dfd9b1bbd553_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7944-9592-41ff017cd370" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019ef121-68ff-7c37-adc0-dfd9b1bbd553" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7944-9592-41ff017cd370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PhantomShareUnitsPSUsMember_019ef121-68ff-7c31-8251-c314e5463fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PhantomShareUnitsPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019ef121-68ff-7944-9592-41ff017cd370" xlink:to="loc_us-gaap_PhantomShareUnitsPSUsMember_019ef121-68ff-7c31-8251-c314e5463fcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019ef121-68ff-7627-94cf-7ce065f5f96e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019ef121-68ff-7627-94cf-7ce065f5f96e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019ef121-68ff-796b-a345-e0c6c8053c53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019ef121-68ff-796b-a345-e0c6c8053c53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_019ef121-68ff-7eab-a104-180d8d93e061" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_019ef121-68ff-7eab-a104-180d8d93e061" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue_019ef121-68ff-7518-bab0-71f34c5e4306" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019ef121-68ff-76c6-8b12-a91d530fe8dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue_019ef121-68ff-7518-bab0-71f34c5e4306" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019ef121-68ff-7177-b4a2-ca726c7ef8d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_LossContingenciesTable_019ef121-68ff-7177-b4a2-ca726c7ef8d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019f1785-d321-7234-87b1-e6e2d2260e53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019ef121-68ff-7177-b4a2-ca726c7ef8d8" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019f1785-d321-7234-87b1-e6e2d2260e53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019f1785-d321-7234-87b1-e6e2d2260e53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019f1785-d321-7234-87b1-e6e2d2260e53" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019f1785-d321-7234-87b1-e6e2d2260e53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019f1785-d321-7d42-ae7a-65f2b8285b60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019f1785-d321-7234-87b1-e6e2d2260e53" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019f1785-d321-7d42-ae7a-65f2b8285b60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_LegalMattersMember_019f1785-d321-7baa-92d6-60fdd800297d" xlink:href="mnr-20260630.xsd#mnr_LegalMattersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019f1785-d321-7d42-ae7a-65f2b8285b60" xlink:to="loc_mnr_LegalMattersMember_019f1785-d321-7baa-92d6-60fdd800297d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_019f1785-d321-70db-bac7-62a88bd08539" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019ef121-68ff-7177-b4a2-ca726c7ef8d8" xlink:to="loc_us-gaap_OtherCommitmentsAxis_019f1785-d321-70db-bac7-62a88bd08539" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_019f1785-d321-70db-bac7-62a88bd08539_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_019f1785-d321-70db-bac7-62a88bd08539" xlink:to="loc_us-gaap_OtherCommitmentsDomain_019f1785-d321-70db-bac7-62a88bd08539_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_019f1785-d321-7789-88c5-fe82c4192162" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_019f1785-d321-70db-bac7-62a88bd08539" xlink:to="loc_us-gaap_OtherCommitmentsDomain_019f1785-d321-7789-88c5-fe82c4192162" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_FutureFirmSalesCommitmentsMember_019f1785-d321-761a-94a7-1fe548f40f3d" xlink:href="mnr-20260630.xsd#mnr_FutureFirmSalesCommitmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_019f1785-d321-7789-88c5-fe82c4192162" xlink:to="loc_mnr_FutureFirmSalesCommitmentsMember_019f1785-d321-761a-94a7-1fe548f40f3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f1785-d321-7055-8d9c-924af9c97889" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f1785-d321-7055-8d9c-924af9c97889" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasDeliveryCommitmentsAndContractsFixedPrice_019f1785-d321-7a6e-8bfa-eb6fb06c2ed0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OilAndGasDeliveryCommitmentsAndContractsFixedPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_OilAndGasDeliveryCommitmentsAndContractsFixedPrice_019f1785-d321-7a6e-8bfa-eb6fb06c2ed0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019f1785-e89c-7e0e-a582-8b3a53fee4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019f1785-e89c-7e0e-a582-8b3a53fee4e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019f1785-e89c-75e3-8bc4-26b66cbd5930" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019f1785-e89c-75e3-8bc4-26b66cbd5930" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_019f1785-e89c-7d1e-aa9c-3ffda5818318" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1785-d321-7c03-9d40-925aa7158b23" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_019f1785-e89c-7d1e-aa9c-3ffda5818318" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/CommitmentsandContingenciesScheduleofVolumeCommitmentsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#CommitmentsandContingenciesScheduleofVolumeCommitmentsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/CommitmentsandContingenciesScheduleofVolumeCommitmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019f1784-abbd-7bd6-bb51-4ea8be052747" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_LossContingenciesTable_019f1784-abbd-7bd6-bb51-4ea8be052747" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_019f1784-abbd-71e7-b5c4-5598f04f621d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019f1784-abbd-7bd6-bb51-4ea8be052747" xlink:to="loc_us-gaap_OtherCommitmentsAxis_019f1784-abbd-71e7-b5c4-5598f04f621d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_019f1784-abbd-71e7-b5c4-5598f04f621d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_019f1784-abbd-71e7-b5c4-5598f04f621d" xlink:to="loc_us-gaap_OtherCommitmentsDomain_019f1784-abbd-71e7-b5c4-5598f04f621d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_019f1784-abbd-7e51-831e-9535d3d04521" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_019f1784-abbd-71e7-b5c4-5598f04f621d" xlink:to="loc_us-gaap_OtherCommitmentsDomain_019f1784-abbd-7e51-831e-9535d3d04521" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_FutureFirmSalesCommitmentsMember_019f1784-abbd-74a2-975a-f4aadf9ef882" xlink:href="mnr-20260630.xsd#mnr_FutureFirmSalesCommitmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_019f1784-abbd-7e51-831e-9535d3d04521" xlink:to="loc_mnr_FutureFirmSalesCommitmentsMember_019f1784-abbd-74a2-975a-f4aadf9ef882" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsFutureMinimumPaymentsRemainderOfFiscalYear_019f1784-abbd-78c7-938c-7a01878dc5fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsFutureMinimumPaymentsRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitmentsFutureMinimumPaymentsRemainderOfFiscalYear_019f1784-abbd-78c7-938c-7a01878dc5fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentDueInNextTwelveMonths_019f1784-abbd-742d-8324-5b381e64bb00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentDueInNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitmentDueInNextTwelveMonths_019f1784-abbd-742d-8324-5b381e64bb00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentDueInSecondYear_019f1784-abbd-7cf9-bd7c-470c49b2a883" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentDueInSecondYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitmentDueInSecondYear_019f1784-abbd-7cf9-bd7c-470c49b2a883" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentDueInThirdYear_019f1784-abbd-7b13-91e0-74eca2f0aa1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentDueInThirdYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitmentDueInThirdYear_019f1784-abbd-7b13-91e0-74eca2f0aa1b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentDueInFourthYear_019f1784-abbd-7d74-840e-453ff45abead" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentDueInFourthYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitmentDueInFourthYear_019f1784-abbd-7d74-840e-453ff45abead" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitment_019f1784-abbd-7dcc-8eb8-285539874a07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1784-abbd-7658-be55-0fc8f1cfb693" xlink:to="loc_us-gaap_OtherCommitment_019f1784-abbd-7dcc-8eb8-285539874a07" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/PartnersCapitalDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#PartnersCapitalDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/PartnersCapitalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityByClassOfStockTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019f83e7-fae4-7120-8e5e-31ab03eb0d21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019f83e7-fae4-7120-8e5e-31ab03eb0d21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7120-8e5e-31ab03eb0d21_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f83e7-fae4-7120-8e5e-31ab03eb0d21" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7120-8e5e-31ab03eb0d21_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f83e7-fae4-7120-8e5e-31ab03eb0d21" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AtTheMarketOfferingMember_019f83e7-fae4-7e20-8467-ca9f58a3bc06" xlink:href="mnr-20260630.xsd#mnr_AtTheMarketOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:to="loc_mnr_AtTheMarketOfferingMember_019f83e7-fae4-7e20-8467-ca9f58a3bc06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PublicOfferingMember_019f83e8-11ca-79c0-bb67-7b32b285e243" xlink:href="mnr-20260630.xsd#mnr_PublicOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:to="loc_mnr_PublicOfferingMember_019f83e8-11ca-79c0-bb67-7b32b285e243" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SecondaryPublicOfferingMember_019f83e8-11ca-7c4c-b372-c98468a66e2a" xlink:href="mnr-20260630.xsd#mnr_SecondaryPublicOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:to="loc_mnr_SecondaryPublicOfferingMember_019f83e8-11ca-7c4c-b372-c98468a66e2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OverAllotmentOptionMember_019f83e8-11ca-7861-a815-f10a630b27a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OverAllotmentOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f83e7-fae4-7ba1-aba6-b334b4b47365" xlink:to="loc_us-gaap_OverAllotmentOptionMember_019f83e8-11ca-7861-a815-f10a630b27a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f83e8-11ca-749d-850e-c43bb63efc27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f83e8-11ca-749d-850e-c43bb63efc27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f83e8-11ca-749d-850e-c43bb63efc27_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f83e8-11ca-749d-850e-c43bb63efc27" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f83e8-11ca-749d-850e-c43bb63efc27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f83e8-11ca-79fe-854e-76f74a50d64b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f83e8-11ca-749d-850e-c43bb63efc27" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f83e8-11ca-79fe-854e-76f74a50d64b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_IKAVAcquisitionMember_019f83e8-11ca-779c-a48b-9881f8aeee0e" xlink:href="mnr-20260630.xsd#mnr_IKAVAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f83e8-11ca-79fe-854e-76f74a50d64b" xlink:to="loc_mnr_IKAVAcquisitionMember_019f83e8-11ca-779c-a48b-9881f8aeee0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_019f83e8-11ca-7d8f-b1b4-620753a47dda" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:to="loc_us-gaap_AssetAcquisitionAxis_019f83e8-11ca-7d8f-b1b4-620753a47dda" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f83e8-11ca-7d8f-b1b4-620753a47dda_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f83e8-11ca-7d8f-b1b4-620753a47dda" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f83e8-11ca-7d8f-b1b4-620753a47dda_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f83e8-11ca-7c94-bbc1-ede065500ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f83e8-11ca-7d8f-b1b4-620753a47dda" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f83e8-11ca-7c94-bbc1-ede065500ecf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SabinalAcquisitionMember_019f83e8-11ca-7a84-9c27-54f30fe8a553" xlink:href="mnr-20260630.xsd#mnr_SabinalAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f83e8-11ca-7c94-bbc1-ede065500ecf" xlink:to="loc_mnr_SabinalAcquisitionMember_019f83e8-11ca-7a84-9c27-54f30fe8a553" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_019f83e8-246a-73c6-ab80-56a1bb408007" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_019ef121-68ff-7ae5-9f0c-52e8bc5193dd" xlink:to="loc_srt_RestatementAxis_019f83e8-246a-73c6-ab80-56a1bb408007" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019f83e8-246a-73c6-ab80-56a1bb408007_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_019f83e8-246a-73c6-ab80-56a1bb408007" xlink:to="loc_srt_RestatementDomain_019f83e8-246a-73c6-ab80-56a1bb408007_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019f83e8-246a-730e-a6f1-1ae29aef0303" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_019f83e8-246a-73c6-ab80-56a1bb408007" xlink:to="loc_srt_RestatementDomain_019f83e8-246a-730e-a6f1-1ae29aef0303" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioPreviouslyReportedMember_019f83e8-246a-77b8-b852-fbc287e8dfa5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioPreviouslyReportedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_019f83e8-246a-730e-a6f1-1ae29aef0303" xlink:to="loc_srt_ScenarioPreviouslyReportedMember_019f83e8-246a-77b8-b852-fbc287e8dfa5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAdjustmentMember_019f83e8-246a-7c3c-9f3d-20055122161a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_019f83e8-246a-730e-a6f1-1ae29aef0303" xlink:to="loc_srt_RestatementAdjustmentMember_019f83e8-246a-7c3c-9f3d-20055122161a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountAggregateOfferingPrice_019f83e7-fae4-7583-882a-2e0d5cc9314d" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountAggregateOfferingPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_mnr_PartnersCapitalAccountAggregateOfferingPrice_019f83e7-fae4-7583-882a-2e0d5cc9314d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnitsSoldInPrivatePlacement_019f83e8-11ca-7efb-be30-5e6b439110d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountUnitsSoldInPrivatePlacement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_PartnersCapitalAccountUnitsSoldInPrivatePlacement_019f83e8-11ca-7efb-be30-5e6b439110d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare_019f83e8-11ca-7fac-baa5-93f0a5039131" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare_019f83e8-11ca-7fac-baa5-93f0a5039131" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits_019f83e8-11ca-7f37-b5f7-968149f10391" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits_019f83e8-11ca-7f37-b5f7-968149f10391" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ProceedsFromIssuanceOfCommonLimitedPartnersUnitsNetOfFeesAndExpenses_019f83e8-11ca-774b-8226-8f3d53238107" xlink:href="mnr-20260630.xsd#mnr_ProceedsFromIssuanceOfCommonLimitedPartnersUnitsNetOfFeesAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_mnr_ProceedsFromIssuanceOfCommonLimitedPartnersUnitsNetOfFeesAndExpenses_019f83e8-11ca-774b-8226-8f3d53238107" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f83e8-11ca-73a4-b0ac-0817a8578694" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f83e8-11ca-73a4-b0ac-0817a8578694" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableShares_019f83e8-11ca-7492-92ad-2445f1b0e874" xlink:href="mnr-20260630.xsd#mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_mnr_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuableShares_019f83e8-11ca-7492-92ad-2445f1b0e874" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f83e8-11ca-70e2-aa5a-6967c7a0b1b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019f83e8-11ca-70e2-aa5a-6967c7a0b1b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f83e8-11ca-7330-a977-647b509a56b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_019f83e8-11ca-7330-a977-647b509a56b9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnits_019f83e8-246a-747b-905f-5ff891ae8290" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PartnersCapitalAccountUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_PartnersCapitalAccountUnits_019f83e8-246a-747b-905f-5ff891ae8290" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountUnitsCancelled_019f83e8-246a-7064-9ab7-d3094b62cec9" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountUnitsCancelled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_mnr_PartnersCapitalAccountUnitsCancelled_019f83e8-246a-7064-9ab7-d3094b62cec9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_019fb617-9f75-7905-b5af-4b82519cfaef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_019fb617-9f75-7905-b5af-4b82519cfaef" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid_019f83e8-246a-757d-b444-badd1a72068b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_019f83e7-fae4-798f-9284-846b2f209d64" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid_019f83e8-246a-757d-b444-badd1a72068b" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_019f17a7-7075-7d4f-b000-87bb167b77a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_019f17a7-7075-7d4f-b000-87bb167b77a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7d4f-b000-87bb167b77a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019f17a7-7075-7d4f-b000-87bb167b77a4" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7d4f-b000-87bb167b77a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019f17a7-7075-7d4f-b000-87bb167b77a4" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ManagementServicesAgreementMachResourcesMember_019f17a7-7075-74da-8ed7-570f07365715" xlink:href="mnr-20260630.xsd#mnr_ManagementServicesAgreementMachResourcesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:to="loc_mnr_ManagementServicesAgreementMachResourcesMember_019f17a7-7075-74da-8ed7-570f07365715" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_April2026SecondaryOfferingMember_019f17a7-86a4-7fc7-a475-2fe49dee9f3f" xlink:href="mnr-20260630.xsd#mnr_April2026SecondaryOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:to="loc_mnr_April2026SecondaryOfferingMember_019f17a7-86a4-7fc7-a475-2fe49dee9f3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_TransitionServicesAgreementsMember_019f17a7-86a4-7271-8578-51328e347df8" xlink:href="mnr-20260630.xsd#mnr_TransitionServicesAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:to="loc_mnr_TransitionServicesAgreementsMember_019f17a7-86a4-7271-8578-51328e347df8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_February2025OfferingMember_019f17a7-86a4-7622-a9c6-4f6977de1c1f" xlink:href="mnr-20260630.xsd#mnr_February2025OfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f17a7-7075-7885-96b2-151f1b0d17e6" xlink:to="loc_mnr_February2025OfferingMember_019f17a7-86a4-7622-a9c6-4f6977de1c1f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f17a7-7075-74cf-92d6-e2156558a90c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f17a7-7075-74cf-92d6-e2156558a90c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f17a7-7075-74cf-92d6-e2156558a90c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f17a7-7075-74cf-92d6-e2156558a90c" xlink:to="loc_us-gaap_RelatedPartyDomain_019f17a7-7075-74cf-92d6-e2156558a90c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f17a7-7075-72a0-926a-5cc59e527ed7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f17a7-7075-74cf-92d6-e2156558a90c" xlink:to="loc_us-gaap_RelatedPartyDomain_019f17a7-7075-72a0-926a-5cc59e527ed7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019f17a7-7075-72ab-ba88-661ce8cd4c65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019f17a7-7075-72a0-926a-5cc59e527ed7" xlink:to="loc_us-gaap_RelatedPartyMember_019f17a7-7075-72ab-ba88-661ce8cd4c65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019f17a7-86a4-7017-845f-0797f945f313" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_srt_CounterpartyNameAxis_019f17a7-86a4-7017-845f-0797f945f313" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-7017-845f-0797f945f313_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019f17a7-86a4-7017-845f-0797f945f313" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-7017-845f-0797f945f313_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-74f2-86ab-26c2fe22cbc1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019f17a7-86a4-7017-845f-0797f945f313" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-74f2-86ab-26c2fe22cbc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_TomL.WardMember_019f17a7-86a4-7650-a9d0-04fc8013688f" xlink:href="mnr-20260630.xsd#mnr_TomL.WardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-74f2-86ab-26c2fe22cbc1" xlink:to="loc_mnr_TomL.WardMember_019f17a7-86a4-7650-a9d0-04fc8013688f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_BCEMachAggregatorMember_019f17a7-86a4-7977-8086-758cd467e315" xlink:href="mnr-20260630.xsd#mnr_BCEMachAggregatorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f17a7-86a4-74f2-86ab-26c2fe22cbc1" xlink:to="loc_mnr_BCEMachAggregatorMember_019f17a7-86a4-7977-8086-758cd467e315" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019f17a7-86a4-77f3-b59a-cf3345cf7c47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019f17a7-86a4-77f3-b59a-cf3345cf7c47" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f17a7-86a4-77f3-b59a-cf3345cf7c47_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f17a7-86a4-77f3-b59a-cf3345cf7c47" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f17a7-86a4-77f3-b59a-cf3345cf7c47_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f17a7-86a4-70bf-bea7-ca1a6ef1263f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f17a7-86a4-77f3-b59a-cf3345cf7c47" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f17a7-86a4-70bf-bea7-ca1a6ef1263f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SecondaryPublicOfferingMember_019f17a7-86a4-788f-a5df-4042a4616397" xlink:href="mnr-20260630.xsd#mnr_SecondaryPublicOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f17a7-86a4-70bf-bea7-ca1a6ef1263f" xlink:to="loc_mnr_SecondaryPublicOfferingMember_019f17a7-86a4-788f-a5df-4042a4616397" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f17a7-86a4-7f60-89ef-692fd1b4f62c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f17a7-86a4-7f60-89ef-692fd1b4f62c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f17a7-86a4-7f60-89ef-692fd1b4f62c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f17a7-86a4-7f60-89ef-692fd1b4f62c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f17a7-86a4-7f60-89ef-692fd1b4f62c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f17a7-86a4-7e2f-9e15-b12d0c8b79b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f17a7-86a4-7f60-89ef-692fd1b4f62c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f17a7-86a4-7e2f-9e15-b12d0c8b79b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_IKAVAcquisitionMember_019f17a7-86a4-7b88-85d1-81c872bc9ba0" xlink:href="mnr-20260630.xsd#mnr_IKAVAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f17a7-86a4-7e2f-9e15-b12d0c8b79b8" xlink:to="loc_mnr_IKAVAcquisitionMember_019f17a7-86a4-7b88-85d1-81c872bc9ba0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_019f17a7-86a4-75b7-8812-d4d6080bb991" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019ef121-68ff-79ed-ba13-5c489303c524" xlink:to="loc_us-gaap_AssetAcquisitionAxis_019f17a7-86a4-75b7-8812-d4d6080bb991" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f17a7-86a4-75b7-8812-d4d6080bb991_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f17a7-86a4-75b7-8812-d4d6080bb991" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f17a7-86a4-75b7-8812-d4d6080bb991_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_019f17a7-86a4-7cbc-a346-f40b11606510" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_019f17a7-86a4-75b7-8812-d4d6080bb991" xlink:to="loc_us-gaap_AssetAcquisitionDomain_019f17a7-86a4-7cbc-a346-f40b11606510" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SabinalAcquisitionMember_019f17a7-86a4-7fe0-a3fd-e06029c162c6" xlink:href="mnr-20260630.xsd#mnr_SabinalAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_019f17a7-86a4-7cbc-a346-f40b11606510" xlink:to="loc_mnr_SabinalAcquisitionMember_019f17a7-86a4-7fe0-a3fd-e06029c162c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ManagementFeeExpenseAnnualFee_019f17a7-7075-7b3b-8503-a29b8549b76e" xlink:href="mnr-20260630.xsd#mnr_ManagementFeeExpenseAnnualFee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_mnr_ManagementFeeExpenseAnnualFee_019f17a7-7075-7b3b-8503-a29b8549b76e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019f17a7-7075-7a9f-a064-59d8d5276915" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019f17a7-7075-7a9f-a064-59d8d5276915" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManagementFeeExpense_019f17a7-7075-7c8d-be30-7995e06c6161" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ManagementFeeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_us-gaap_ManagementFeeExpense_019f17a7-7075-7c8d-be30-7995e06c6161" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019f17a7-86a4-7ed2-9d0e-36b9412be384" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_us-gaap_AccountsPayableCurrent_019f17a7-86a4-7ed2-9d0e-36b9412be384" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_RelatedPartyTransactionPurchasesFromRelatedPartyShares_019f17a7-86a4-76ae-87e1-8d54c0f478d3" xlink:href="mnr-20260630.xsd#mnr_RelatedPartyTransactionPurchasesFromRelatedPartyShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_mnr_RelatedPartyTransactionPurchasesFromRelatedPartyShares_019f17a7-86a4-76ae-87e1-8d54c0f478d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare_019f17a7-86a4-714b-bd9d-b25efde0d930" xlink:href="mnr-20260630.xsd#mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_mnr_PartnersCapitalAccountUnitsSoldInPrivatePlacementPricePerShare_019f17a7-86a4-714b-bd9d-b25efde0d930" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_RelatedPartyTransactionsPaymentsForTransitionServices_019f17a7-86a4-787d-8aef-f2691e1e050a" xlink:href="mnr-20260630.xsd#mnr_RelatedPartyTransactionsPaymentsForTransitionServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_mnr_RelatedPartyTransactionsPaymentsForTransitionServices_019f17a7-86a4-787d-8aef-f2691e1e050a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits_019f17a7-86a4-7a3d-ac91-5230e54e3a37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f17a7-7075-7fe0-9e31-4d2442ab8a58" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits_019f17a7-86a4-7a3d-ac91-5230e54e3a37" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/SegmentInformationDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#SegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/SegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef121-68ff-7be1-9cc6-0295b457f73c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef121-68ff-7be1-9cc6-0295b457f73c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019ef121-68ff-7078-b4fa-8cb03efe422d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef121-68ff-7be1-9cc6-0295b457f73c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019ef121-68ff-7078-b4fa-8cb03efe422d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef121-68ff-7078-b4fa-8cb03efe422d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef121-68ff-7078-b4fa-8cb03efe422d" xlink:to="loc_us-gaap_SegmentDomain_019ef121-68ff-7078-b4fa-8cb03efe422d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef121-68ff-7ef8-a76b-9f50daa780d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef121-68ff-7078-b4fa-8cb03efe422d" xlink:to="loc_us-gaap_SegmentDomain_019ef121-68ff-7ef8-a76b-9f50daa780d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_ReportableSegmentMember_019ef121-68ff-7ab9-a034-06599f45e90d" xlink:href="mnr-20260630.xsd#mnr_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef121-68ff-7ef8-a76b-9f50daa780d1" xlink:to="loc_mnr_ReportableSegmentMember_019ef121-68ff-7ab9-a034-06599f45e90d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ef121-68ff-7438-847a-cbca536117ee" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef121-68ff-7be1-9cc6-0295b457f73c" xlink:to="loc_srt_ProductOrServiceAxis_019ef121-68ff-7438-847a-cbca536117ee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68ff-7438-847a-cbca536117ee_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68ff-7438-847a-cbca536117ee" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68ff-7438-847a-cbca536117ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef121-68ff-76c8-ab0d-d44ce75ba022" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ef121-68ff-7438-847a-cbca536117ee" xlink:to="loc_srt_ProductsAndServicesDomain_019ef121-68ff-76c8-ab0d-d44ce75ba022" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68ff-7843-8361-0655f4645ced" xlink:href="mnr-20260630.xsd#mnr_OilGasAndNaturalGasLiquidsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68ff-76c8-ab0d-d44ce75ba022" xlink:to="loc_mnr_OilGasAndNaturalGasLiquidsNetMember_019ef121-68ff-7843-8361-0655f4645ced" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NaturalGasMidstreamMember_019ef121-68ff-709e-93e6-9250392ed6c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NaturalGasMidstreamMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68ff-76c8-ab0d-d44ce75ba022" xlink:to="loc_us-gaap_NaturalGasMidstreamMember_019ef121-68ff-709e-93e6-9250392ed6c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019ef121-68ff-710c-b667-59147ca2ff84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef121-68ff-76c8-ab0d-d44ce75ba022" xlink:to="loc_us-gaap_ProductMember_019ef121-68ff-710c-b667-59147ca2ff84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68ff-78db-9847-39f43ff51e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef121-68ff-7be1-9cc6-0295b457f73c" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68ff-78db-9847-39f43ff51e1a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-78db-9847-39f43ff51e1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68ff-78db-9847-39f43ff51e1a" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-78db-9847-39f43ff51e1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-7d6c-aa21-c00ae3184f92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019ef121-68ff-78db-9847-39f43ff51e1a" xlink:to="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-7d6c-aa21-c00ae3184f92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_019ef121-68ff-7408-a38a-4b7c55d3279b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-7d6c-aa21-c00ae3184f92" xlink:to="loc_us-gaap_NonrelatedPartyMember_019ef121-68ff-7408-a38a-4b7c55d3279b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019ef121-68ff-7ce3-a29a-cb5144331f26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019ef121-68ff-7d6c-aa21-c00ae3184f92" xlink:to="loc_us-gaap_RelatedPartyMember_019ef121-68ff-7ce3-a29a-cb5144331f26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019ef121-68ff-7ded-96ac-736c333ce6b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_Revenues_019ef121-68ff-7ded-96ac-736c333ce6b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019ef121-68ff-7d1a-8071-fe73fe3e7a4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019ef121-68ff-7d1a-8071-fe73fe3e7a4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResultsOfOperationsProductionOrLiftingCosts_019ef121-68ff-7ee8-b2e7-aac12a1c9c78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResultsOfOperationsProductionOrLiftingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_ResultsOfOperationsProductionOrLiftingCosts_019ef121-68ff-7ee8-b2e7-aac12a1c9c78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductionTaxExpense_019ef121-68ff-786e-9dba-b3a082b1e249" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductionTaxExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_ProductionTaxExpense_019ef121-68ff-786e-9dba-b3a082b1e249" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_SignificantExpenses_019ef121-68ff-751b-bbf5-60ff0eb032bb" xlink:href="mnr-20260630.xsd#mnr_SignificantExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_mnr_SignificantExpenses_019ef121-68ff-751b-bbf5-60ff0eb032bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepletionOfOilAndGasProperties_019ef121-68ff-7448-8c33-b4076e98610f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepletionOfOilAndGasProperties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_DepletionOfOilAndGasProperties_019ef121-68ff-7448-8c33-b4076e98610f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDepreciationAndAmortization_019ef121-68ff-7ae1-a528-dd9b70443f66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_OtherDepreciationAndAmortization_019ef121-68ff-7ae1-a528-dd9b70443f66" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019ef121-68ff-7fc2-9ff3-571dcf545c29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019ef121-68ff-7fc2-9ff3-571dcf545c29" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019ef121-68ff-7613-a7b2-e080817aa38e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019ef121-68ff-7613-a7b2-e080817aa38e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019ef121-68ff-7f3d-aa71-359fa2ab5764" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019ef121-68ff-7f3d-aa71-359fa2ab5764" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef121-68ff-764a-ad0f-eb2d33d455ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef121-68ff-764a-ad0f-eb2d33d455ae" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_mnr_NonoperatingIncomeExpenseAdjusted_019ef121-68ff-7720-8f25-4c02702478e4" xlink:href="mnr-20260630.xsd#mnr_NonoperatingIncomeExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_mnr_NonoperatingIncomeExpenseAdjusted_019ef121-68ff-7720-8f25-4c02702478e4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019ef121-68ff-7c79-a3e6-a6594e5bc353" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_NetIncomeLoss_019ef121-68ff-7c79-a3e6-a6594e5bc353" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019f2597-0a76-759e-bcf5-5beb1893afed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019f2597-0a76-759e-bcf5-5beb1893afed" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019ef121-68ff-7668-821c-4e2c5092f620" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef121-68ff-72e4-a7d7-573df1c2fba2" xlink:to="loc_us-gaap_Assets_019ef121-68ff-7668-821c-4e2c5092f620" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://machnaturalresources.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="mnr-20260630.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://machnaturalresources.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019ef121-68ff-7b1e-b3f1-3559a153394f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019ef121-68ff-7a61-93e1-a6e893694cd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019ef121-68ff-7b1e-b3f1-3559a153394f" xlink:to="loc_us-gaap_SubsequentEventTable_019ef121-68ff-7a61-93e1-a6e893694cd0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019ef121-68ff-72c4-950d-7706c66d0e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019ef121-68ff-7a61-93e1-a6e893694cd0" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019ef121-68ff-72c4-950d-7706c66d0e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019ef121-68ff-72c4-950d-7706c66d0e7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019ef121-68ff-72c4-950d-7706c66d0e7e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019ef121-68ff-72c4-950d-7706c66d0e7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019ef121-68ff-78ac-b6ca-7fc4c5da44f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019ef121-68ff-72c4-950d-7706c66d0e7e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019ef121-68ff-78ac-b6ca-7fc4c5da44f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019ef121-68ff-778b-a109-e8c0fb686b3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019ef121-68ff-78ac-b6ca-7fc4c5da44f3" xlink:to="loc_us-gaap_SubsequentEventMember_019ef121-68ff-778b-a109-e8c0fb686b3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_019ef121-68ff-722b-8226-5e9e29685a04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019ef121-68ff-7b1e-b3f1-3559a153394f" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_019ef121-68ff-722b-8226-5e9e29685a04" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
