espouse v.

1650s, from Late Latin sponsor "sponsor in baptism," in Latin "a surety, guarantee, bondsman," from sponsus, past participle of spondere "give assurance, promise solemnly," from Proto-Italic *spondejo- "to pledge," literally "to libate many times," from PIE *spondeio- "to libate" (source also of Hittite ishpanti- "to bring a fluid sacrifice, pour;" Greek spendein "make a drink offering," spondē "libation, offering of wine;" compare spondee). Sense of "person who pays for a radio (or, after 1947, TV) program" is first recorded 1931.

the later Romans evidently found words beginning in sc-, sp-, st- difficult or unpleasant to pronounce; in Late Latin forms begin to emerge in i- (such as ispatium, ispiritu), and from 5c. this shifted to e-. The development was carried into the Romanic languages, especially Old French, and the French words were modified further after 15c. by natural loss of -s- (the suppression being marked by an acute accent on the e-), while in other cases the word was formally corrected back to the Latin spelling (for example spécial). Hence French état for Old French estat for Latin status, etc. It also affected Romanic borrowings from Germanic (such as espy, eschew).

A different e- is a reduced form of Latin ex- before consonants (see ex-), and the e- in enough is an unfelt survival of an Old English alternative form of ge-.

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.