Matrimony

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late Middle English: via Old French from Latin matrimonium, based on mater, matr- ‘mother’.

wiktionary

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From Old French matremoine, from Latin mātrimōnium(“marriage, wedlock”), from māter(“mother”) + -mōnium(“obligation”). Also matri- +‎ -mony. Compare patrimony

etymonline

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matrimony (n.)

c. 1300, matrimoine, "the married state, the relation of husband and wife, wedlock; the sacrament of marriage," from Old French matremoine "matrimony, marriage" and directly from Latin mātrimōnium "wedlock, marriage" (in plural "wives"), from mātrem (nominative māter) "mother" (see mother (n.1)) + -mōnium, suffix signifying "action, state, condition."