(v.) To nullify; to deny; to make ineffective\.

abate abnegate abolish abrogate agree to disagree annihilate annul be at cross-purposes be contrary to be unmoved be unwilling beg off belie blow sky-high blow up break break off bring to naught bring to nothing buffer call into question cancel cancel out challenge clash collide come to nothing conflict contest contradict contravene controvert counter counteract counterbalance countercheck cross decline decline to accept deflate deny differ disaccord disaffirm disagree disallow disbelieve disclaim disconfirm discredit disprove dissent explode expose frustrate gag on gainsay hold out against impugn invalidate jangle jar jostle misbelieve mismatch mismate negativate negative neutralize not admit not believe not buy not consent not hear of not swallow not think of nullify object offset oppugn prove the contrary puncture quash rebut redress refuse refuse consent refuse to admit refuse to credit reject repeal repudiate resist entreaty resist persuasion revoke say nay say no shake the head show up stand aloof stultify thwart traverse turn down unbelieve undercut undo vary vitiate void vote nay vote negatively