The Collaborative International Dictionary of English v.0.48:

Litigation \Lit`i*ga"tion\, n. [L. litigatio, fr. litigare to
   dispute, litigate; lis, litis, dispute, lawsuit (OL. stlis) +
   agere to carry on. See Agent.]
   The act or process of litigating; a suit at law; a judicial
   contest.
   [1913 Webster]

WordNet (r) 3.0 (2006):

litigation
    n 1: a legal proceeding in a court; a judicial contest to
         determine and enforce legal rights [syn: litigation,
         judicial proceeding]

The Devil's Dictionary (1881-1906):

LITIGATION, n.  A machine which you go into as a pig and come out of
as a sausage.