The Collaborative International Dictionary of English v.0.48:

Retaliatory \Re*tal"i*a*to*ry\, a.
   Tending to, or involving, retaliation; retaliative; as
   retaliatory measures.
   [1913 Webster]

WordNet (r) 3.0 (2006):

retaliatory
    adj 1: of or relating to or having the nature of retribution;
           "retributive justice demands an eye for an eye" [syn:
           retaliatory, relatiative, retributive,
           retributory, vindicatory]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "retaliatory":
   amendatory, avenging, balancing, changeable, commutable,
   commutative, compensating, compensatory, convertible,
   counteracting, counteractive, counterbalancing, countervailing,
   equal, equalizing, equivalent, even, exchanged, expiatory,
   give-and-take, grudgeful, implacable, indemnificatory,
   interchangeable, interchanged, irreconcilable, mutual, offsetting,
   penitential, permutable, punitive, punitory, rancorous, reciprocal,
   reciprocating, reciprocative, recompensing, recompensive,
   rectifying, reparative, restitutive, retaliative, retributive,
   retributory, returnable, revanchist, revengeful, standard, swapped,
   switched, traded, transposed, unappeasable, vengeful, vindicatory,
   vindictive