NOUN (1)

1. a claim filed in opposition to another claim in a legal action;


VERB (1)

1. set up a claim in opposition to a previous claim;

The Collaborative International Dictionary of English v.0.48:

Counterclaim \Coun"ter*claim`\ (-kl[=a]m`), n. (Law)
   A claim made by a person as an offset to a claim made on him.
   [1913 Webster]

WordNet (r) 3.0 (2006):

counterclaim
    n 1: a claim filed in opposition to another claim in a legal
         action
    v 1: set up a claim in opposition to a previous claim

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "counterclaim":
   confutation, confute, contraremonstrance, counteraccusation,
   counterblast, countercharge, counterdemand, counterreply,
   counterstatement, defense, make a rebuttal, rebut, rebuttal,
   rebutter, refutation, refute, rejoin, rejoinder, replication,
   surrebut, surrebuttal, surrebutter, surrejoin, surrejoinder