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):

recognizance
    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]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "recognizance":
   agreement, arrangement, bail, bond, commitment, contract,
   contract by deed, contract of record, contract quasi,
   covenant of indemnity, debenture, debenture bond, deed,
   deed of trust, deed poll, earnest, earnest money, engagement,
   escrow, formal contract, gage, group policy, handsel, hock,
   hostage, implied contract, indent, indenture, insurance policy,
   mainprise, mortgage deed, obligation, parol contract, pawn, pignus,
   pledge, policy, preengagement, promissory note, replevin, replevy,
   special contract, specialty, specialty contract, surety,
   title deed, token payment, understanding, undertaking, vadimonium,
   vadium, verbal agreement



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RECOGNIZANCE, contracts. An obligation of record entered into before a court
or officer duly authorized for that purpose, with a condition to do some act
required by law, which is therein specified. 2 Bl. Com. 341; Bro. Ab. h.t.;
Dick. Just. h.t.; 1 Chit. Cr. Law, 90.
     2. Recognizances relate either to criminal or civil matters. 1.
Recognizances in criminal cases, are either that the party shall appear
before the proper court to answer to such charges as are or shall be made
against him, that he shall keep the peace or be of good behaviour. Witnesses
are also required to be bound in a recognizance to testify.
     3.-2. In civil cases, recognizances are entered into by bail,
conditioned that they will pay the debt, interest and costs recovered by the
plaintiff under certain contingencies. There are also cases where
recognizances are entered into under the authority and requirements of
statutes.
     4. As to the form. The party need not sign it; the court, judge or
magistrate having authority to take the same, makes a short memorandum on
the record, which is sufficient. 2 Binn. R. 481; 1 Chit. Cr. Law, 90; 2
Wash. C. C. R. 422; 9 Mass. 520; 1 Dana, 523; 1 Tyler, 291; 4 Vern. 488; 1
Stew. & Port. 465; 7 Vern. 529; 2 A. R. Marsh. 131; 5 S. & R. 147; Vide
generally, Com. Dig. Forcible Entry, D 27; Id. Obligation, K; Whart. Dig.
h.t. Vin. Ab. h.t.; Rolle's Ab. h.t.; 2 Wash. C. C. Rep. 422; Id. 29; 2
Yeates, R. 437; 1 Binn. R. 98, note 1 Serg. & Rawle, 328 3 Yeates, R. 93;
Burn. Just. h.t. Vin. Ab. h.t.; 2 Sell. Pract. 45.