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
   Truth.]
   1. To contract to any one for a marriage; to engage or
      promise in order to marriage; to affiance; -- used esp. of
      a woman.
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            He, in the first flower of my freshest age,
            Betrothed me unto the only heir.      --Spenser.
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            Ay, and we are betrothed.             --Shak.
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   2. To promise to take (as a future spouse); to plight one's
      troth to.
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            What man is there that hath betrothed a wife, and
            hath not taken her?                   --Deut. xx. 7.
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   3. To nominate to a bishopric, in order to consecration.
      --Ayliffe.
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