exogamy

From exo- +‎ -gamy. Coined by British lawyer and ethnologist John Ferguson McLennan in his Studies in Ancient History, page 25.^[1]

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exogamy

Wikipedia

exogamy (countable and uncountable, plural exogamies)

1. marriage to a person belonging to a tribe or group other than one's own as required by custom or law

   Synonyms: see Thesaurus:intermarriage

   Antonyms: endogamy; see also Thesaurus:intermarriage

2. (biology) the fusion of two unrelated gametes

   Antonym: endogamy

• exogamous

• intermarriage