annul
Cross references:
1. nullify
an.nul \*-'n*l\ vt or an.nulled; or an.nul.ling [ME annullen, fr. MF
annuller, fr. LL annullare, fr. L ad-] + nullus not any - more at NULL 1:
to reduce to nothing : OBLITERATE 2: to make ineffective or inoperative :
NEUTRALIZE {~ the drug's effect} 3: to declare or make legally void
Webster's English Dictionary