espousal (n.)

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 sponsor (n.)). Extended sense of "adopt, embrace" a cause, party, etc., is from 1620s. Related: Espoused; espouses; espousing. For initial e-, see e-.

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-.