The Collaborative International Dictionary of English v.0.48:

Espousal \Es*pous"al\, n. [OF. espousailles, pl., F.
   ['e]pousailles, L. sponsalia, fr. sponsalis belonging to
   betrothal or espousal. See Espouse, and cf. Sponsal,
   Spousal.]
   1. The act of espousing or betrothing; especially, in the
      plural, betrothal; plighting of the troths; a contract of
      marriage; sometimes, the marriage ceremony.
      [1913 Webster]

   2. The uniting or allying one's self with anything;
      maintenance; adoption; as, the espousal of a quarrel.
      [1913 Webster]

            The open espousal of his cause.       --Lord Orford.
      [1913 Webster]

WordNet (r) 3.0 (2006):

espousal
    n 1: archaic terms for a wedding or wedding feast [syn:
         bridal, espousal]
    2: the act of becoming betrothed or engaged [syn: betrothal,
       espousal]
    3: the act of accepting with approval; favorable reception; "its
       adoption by society"; "the proposal found wide acceptance"
       [syn: adoption, acceptance, acceptation, espousal]