ban call on contradict oppose rebuff refuse refute reject revoke turn down withhold abjure abnegate begrudge contravene controvert curb disallow disavow disbelieve discard disclaim discredit disown disprove doubt eschew exclude forbid forgo forsake gainsay negate negative nullify rebut recant repudiate restrain sacrifice spurn taboo veto disacknowledge enjoin from hold back keep back not buy say no to take exception to turn thumbs down