betroth (v.)

c. 1300, betrouthen, "to promise to marry (a woman)," from be-, here probably with a sense of "thoroughly," + Middle English treowðe "truth," from Old English treowðe "truth, a pledge" (see truth). From 1560s as "contract to give (a woman) in marriage to another, affiance." Related: Betrothed; betrothing.