Verbs

(v)invalidate, annul, quash, void, avoid, nullifydeclare invalid“The contract was annulled”, “void a plea”
(v)invalidate, nullifyshow to be invalid
(v)neutralize, neutralise, nullify, negatemake ineffective by counterbalancing the effect of“Her optimism neutralizes his gloom”, “This action will negate the effect of my efforts”