WordNet (r) 3.0 (2006):

counterattack
    n 1: an attack by a defending force against an attacking enemy
         force in order to regain lost ground or cut off enemy
         advance units etc. [syn: counterattack, countermove]
    2: (chess) an attack that is intended to counter the opponent's
       advantage in another part of the board [syn: counterattack,
       counterplay]
    v 1: make a counterattack [syn: counterattack,
         counterstrike]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "counterattack":
   aggravated assault, aggression, amphibious attack, armed assault,
   assailing, assailment, assault, attack, backfire, banzai attack,
   blitz, blitzkrieg, breakthrough, charge, comeback, counterblast,
   counterblow, counterfire, counterinsurgency, countermeasure,
   counteroffensive, counterrevolution, counterstep, counterstroke,
   coup de main, crippling attack, dead set at, defense, descent on,
   diversion, diversionary attack, drive, flank attack,
   frontal attack, gas attack, head-on attack, infiltration,
   lightning attack, lightning war, mass attack, megadeath, mugging,
   offense, offensive, onset, onslaught, overkill, panzer warfare,
   push, retort, run against, run at, rush, sally, shock tactics,
   sortie, strike, unprovoked assault