setoff

setoff (offset) n. a claim by a defendant in a lawsuit that the plaintiff (party filing the original suit) owes the defendant money which should be subtracted from the amount of damages claimed by plaintiff. By claiming a setoff the defendant does not necessarily deny the plaintiff's original demand, but he/she claims the right to prove the plaintiff owes him/her an amount of money from some other transaction and that the amount should be deducted from the plaintiff's claim. (See: offset, affirmative defense)