'negate' definitions:

Definition of 'negate'

From: WordNet
verb
Be in contradiction with [syn: contradict, belie, negate]
verb
Deny the truth of [syn: contradict, negate, contravene]
verb
Prove negative; show to be false [syn: negate, contradict] [ant: affirm, confirm, corroborate, substantiate, support, sustain]
verb
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]

Synonyms of 'negate'

From: Moby Thesaurus