Source : Webster's Revised Unabridged Dictionary (1913)

Litigate \Lit"i*gate\, v. t. [imp. & p. p. {Litigated}; p. pr. &
   vb. n. {Litigating}.] [See {Litigation}.]
   To make the subject of a lawsuit; to contest in law; to
   prosecute or defend by pleadings, exhibition of evidence, and
   judicial debate in a court; as, to litigate a cause.

Litigate \Lit"i*gate\, v. i.
   To carry on a suit by judicial process.

Source : WordNet®

litigate
     v 1: engage in legal proceedings
     2: institute legal proceedings against; file a suit against;
        "He was warned that the district attorney would process
        him"; "She actioned the company for discrimination" [syn:
        {action}, {sue}, {process}]