The Collaborative International Dictionary of English v.0.48:

Rebuttal \Re*but"tal\ (r[-e]*b[u^]t"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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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, rebuttal]