Nullify - Definition

v 1: declare invalid; "The contract was annulled"; "void a plea"
[syn: invalidate, annul, quash, void, avoid,
nullify] [ant: formalise, formalize, validate]
2: show to be invalid [syn: invalidate, nullify] [ant:
validate]
3: make ineffective by counterbalancing the effect of; "Her
optimism neutralizes his gloom"; "This action will negate the
effect of my efforts" [syn: neutralize, neutralise,
nullify, negate]