The Collaborative International Dictionary of English v.0.48:
Betroth \Be*troth"\, v. t. [imp. & p. p. Betrothed; p. pr. &
vb. n. Betrothing.] [Pref. be- + troth, i. e., truth. See
1. To contract to any one for a marriage; to engage or
promise in order to marriage; to affiance; -- used esp. of
He, in the first flower of my freshest age,
Betrothed me unto the only heir. --Spenser.
Ay, and we are betrothed. --Shak.
2. To promise to take (as a future spouse); to plight one's
What man is there that hath betrothed a wife, and
hath not taken her? --Deut. xx. 7.
3. To nominate to a bishopric, in order to consecration.