1610s, "practice of marrying only once in a lifetime," from French monogamie, from Late Latin monogamia, from Greek monogamia "single marriage," from monogamos "marrying only once," from monos "single, alone" (from PIE root *men- (4) "small, isolated") + gamos "marriage" (see gamete). As "condition of being married to only one person at a time," by 1708.
of humans, "having or permitted to have but one living and undivorced wife or husband at a time," 1778 (of animal pairings from 1770), from Medieval Latin monogamus, from Greek monogamos "marrying only once" (see monogamy). Also sometimes "not remarrying after the death of a spouse." Related: Monogamist (1650s); monogamistic.