betroth

Meanings

1. Of a man: to promise to take (a woman) as a future spouse; to plight one's troth to.
2. Often of a parent or guardian: to promise that (two people) be married to each other; specifically and chiefly, to promise that (a woman) be given in marriage to a man; to affiance.
3. Of God: to enter into a relationship with (believers, or the church as a whole); also, of a priest: to pledge (himself) to the church prior to being consecrated as a bishop.
4. To pledge or promise oneself to (a cause); to espouse; also (sometimes reflexive), to pledge or promise (oneself or one's efforts) to a cause or to do something.

Etymology

From Middle English bitrouthen, bitreuthen (“of a man: to pledge to marry; to give (a woman) in marriage, arrange the marriage of”), from bi- (prefix forming transitive verbs from nouns) + trouth, treuthe (“faithfulness, fidelity, specifically marital fidelity; promise, undertaking, specifically a promise of marriage; truth; etc.”) (from Old English trīewþ, trēowþ (“fidelity; good faith, honour; assurance of good faith, covenant, troth; truth”), from Proto-Germanic *triwwiþō (“contract; promise”), from Proto-Indo-European *dóru (“tree; hence, firm, hard; faithful, true”)), possibly modelled after Old English trēowsian (“to pledge oneself; to prove oneself to be true”)). By surface analysis, be- + troth.