The Collaborative International Dictionary of English v.0.48:

Retaliation \Re*tal`i*a"tion\, n.
   The act of retaliating, or of returning like for like;
   retribution; now, specifically, the return of evil for evil;
   e.g., an eye for an eye, a tooth for a tooth.
   [1913 Webster]

         God . . . takes what is done to others as done to
         himself, and by promise obloges himself to full
         retaliation.                             --Calamy.
   [1913 Webster]

   Syn: Requital; reprisal; retribution; punishment.
        [1913 Webster]

WordNet (r) 3.0 (2006):

retaliation
    n 1: action taken in return for an injury or offense [syn:
         retaliation, revenge]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "retaliation":
   alternation, amends, atonement, avengement, avenging, balancing,
   battledore and shuttlecock, blood feud, blow for blow, commutation,
   compensation, cooperation, correction, counteraction,
   counterbalancing, counterblow, counterchange, cross fire,
   discipline, exchange, expiation, feud, getting even, give-and-take,
   indemnification, indemnity, interchange, intermutation, interplay,
   lex talionis, measure for measure, mutual admiration,
   mutual support, mutual transfer, mutuality, offsetting,
   permutation, punishment, quid pro quo, reciprocality,
   reciprocation, reciprocity, recompense, rectification, redress,
   reparation, repayment, reprisal, requital, restitution,
   retribution, revanche, revanchism, revenge, satisfaction,
   something for something, substitution, sweet revenge, tit for tat,
   transposal, transposition, vendetta, vengeance



The Devil's Dictionary (1881-1906):

RETALIATION, n.  The natural rock upon which is reared the Temple of
Law.