The Collaborative International Dictionary of English v.0.48:

Litigant \Lit"i*gant\, a. [L. litigans, -antis, p. pr. of
   litigare: cf. F. litigant. See Litigate.]
   Disposed to litigate; contending in law; engaged in a
   lawsuit; as, the parties litigant. --Ayliffe.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Litigant \Lit"i*gant\, n.
   A person engaged in a lawsuit.
   [1913 Webster]

WordNet (r) 3.0 (2006):

litigant
    n 1: (law) a party to a lawsuit; someone involved in litigation;
         "plaintiffs and defendants are both litigants" [syn:
         litigant, litigator]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "litigant":
   accessory, accused, actionable, appellant, appellee, bitter-ender,
   brawler, causidical, defendant, diehard, disputant, dissentient,
   dissident, intransigent, irreconcilable, last-ditcher, litigable,
   litigationist, litigator, litigatory, litigious, naysayer,
   negativist, noncooperator, objector, obstructionist, obstructive,
   opposer, oppositionist, panel, parties litigant, party, petitioner,
   plaintiff, protester, quarreler, resister, scrapper, suitor,
   witness, wrangler



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

LITIGANT. One engaged in a suit; one fond of litigation.



The Devil's Dictionary (1881-1906):

LITIGANT, n.  A person about to give up his skin for the hope of
retaining his bones.