c. 1200, "a married person, either one of a married pair, but especially a married woman in relation to her husband," also "Christ or God as the spiritual husband of the soul, the church, etc.," also "marriage, the wedded state," from Old French spous (fem. spouse) "marriage partner," variant of espous/espouse (Modern French épous/épouse), from Latin sponsus "bridegroom" (fem. sponsa "bride"), literally "betrothed," from masc. and fem. past participle of spondere "to bind oneself, promise solemnly," from PIE *spend- "to make an offering, perform a rite" (see sponsor (n.)). Spouse-breach (early 13c.) was an old name for "adultery."
"formally wedded, united in wedlock, having a spouse," late 14c., past-participle adjective from marry (v.).
late 14c., from Old French esposailles (plural) "act of betrothal" (12c., Modern French époussailles), from Latin sponsalia "betrothal, espousal, wedding," noun use of neuter plural of sponsalis "of a betrothal," from sponsa "spouse" (see espouse). For the -e- see e-. Figuratively, of causes, principles, etc., from 1670s.
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.