Why is the ninth month called September?
mid-15c., "to take as spouse, marry," from Old French espouser "marry, take in marriage, join in marriage" (11c., Modern French épouser), from Latin sponsare, past participle of spondere (see espousal).
Extended sense of "adopt, embrace" a cause, party, etc., is from 1620s. Related: Espoused; espouses; espousing. For initial e-, see especial.
(2 Sam. 3:14), to betroth. The espousal was a ceremony of betrothing, a formal agreement between the parties then coming under obligation for the purpose of marriage. Espousals are in the East frequently contracted years before the marriage is celebrated. It is referred to as figuratively illustrating the relations between God and his people (Jer. 2:2; Matt. 1:18; 2 Cor. 11:2). (See BETROTH.)