[1] : The Collaborative International Dictionary of English v.0.48

betrothal \betroth"al\, n.
   the act of betrothing, or the fact of being betrothed; a
   mutual promise, engagement, or contract for a future marriage
   between the persons betrothed; betrothment; affiance. "the
   feast of betrothal." --longfellow.
   1913 webster

[2] : WordNet (r) 2.0

betrothal
     n 1: a mutual promise to marry syn: troth, engagement
     2: the act of becoming betrothed or engaged syn: espousal
see also:
troth engagement espousal 

Betrothal >> B Words
Betrothal, definition of term: Betrothal
betrothal_pag1.html