Source : Webster's Revised Unabridged Dictionary (1913)

Rebuttal \Re*but"tal\, n. (Law)
   The giving of evidence on the part of a plaintiff to destroy
   the effect of evidence introduced by the defendant in the
   same suit.

Source : WordNet®

rebuttal
     n 1: the speech act of refuting by offering a contrary contention
          or argument
     2: (law) a pleading by the defendant in reply to a plaintiff's
        surrejoinder [syn: {rebutter}]