Synonyms/Hypernyms (Ordered by Estimated Frequency) of verb nullify

3 senses of nullify

Sense 1
invalidate, annul, quash, void, avoid, nullify -- (declare invalid; "The contract was annulled"; "void a plea")
       => cancel, strike down -- (declare null and void; make ineffective; "Cancel the election results"; "strike down a law")

Sense 2
invalidate, nullify -- (show to be invalid)
       => negate, contradict -- (prove negative; show to be false)

Sense 3
neutralize, neutralise, nullify, negate -- (make ineffective by counterbalancing the effect of; "Her optimism neutralizes his gloom"; "This action will negate the effect of my efforts")
       => weaken -- (lessen the strength of; "The fever weakened his body")