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.
Proto-Indo-European root meaning "small, isolated."
It forms all or part of: malmsey; manometer; monad; monarchy; monastery; monism; monist; monk; mono; mono-; monoceros; monochrome; monocle; monocular; monogamy; monogram; monolith; monologue; monomania; Monophysite; monopoly; monosyllable; monotony.
It is the hypothetical source of/evidence for its existence is provided by: Greek monos "single, alone," manos "rare, sparse;" Armenian manr "thin, slender, small."