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 "make an offering, perform a rite, promise secretly," hence "to engage oneself by ritual act" (see spondee). Extended sense of "adopt, embrace" a cause, party, etc., is from 1620s. Related: Espoused; espouses; espousing. For initial e-, see e-.