The Collaborative International Dictionary of English v.0.48:

Recognizance \Re*cog"ni*zance\ (r[-e]*k[o^]g"n[i^]*zans or
   r[-e]*k[o^]n"[i^]-), n. [F. reconnaissance, OF.
   recognoissance, fr. recognoissant, p. pr. of recognoistre to
   recognize, F. reconna[^i]tre, fr. L. recognoscere; pref. re-
   re- + cognoscere to know. See Cognizance, Know, and cf.
   Recognize, Reconnoissance.] [Written also
   recognisance.]
   1. (Law)
      (a) An obligation of record entered into before some court
          of record or magistrate duly authorized, with
          condition to do some particular act, as to appear at
          the same or some other court, to keep the peace, or
          pay a debt. A recognizance differs from a bond, being
          witnessed by the record only, and not by the party's
          seal.
      (b) The verdict of a jury impaneled upon assize. --Cowell.
          [1913 Webster]

   Note: Among lawyers the g in this and the related words
         (except recognize) is usually silent.
         [1913 Webster]

   2. A token; a symbol; a pledge; a badge.
      [1913 Webster]

            That recognizance and pledge of love
            Which I first gave her.               --Shak.
      [1913 Webster]

   3. Acknowledgment of a person or thing; avowal; profession;
      recognition.
      [1913 Webster]

WordNet (r) 3.0 (2006):

recognisance
    n 1: (law) a security entered into before a court with a
         condition to perform some act required by law; on failure
         to perform that act a sum is forfeited [syn:
         recognizance, recognisance]