to render or declare legally void or inoperative

to nullify a contract.

to deprive (something) of value or effectiveness; make futile or of no consequence.

verb

affirm , pass , sanctify , validate

verb

abate , abolish , abrogate , annihilate , annul , ax , blue pencil , bring to naught , call all bets off , compensate , confine , counteract , counterbalance , countervail , disannul , forget it , invalidate , kill * , limit , negate , neutralize , nig , offset , quash * , render null and void , renege , renig , repeal , rescind , restrict , scratch * , scrub * , squash * , stamp out * , take out * , torpedo * , trash * , undo , veto , vitiate , void , wash out * , wipe out * , zap * , cancel , set aside , countermand , null , revoke , squash