NULLIFY

neutralize, neutralise, nullify, negate

(verb) make ineffective by counterbalancing the effect of; “Her optimism neutralizes his gloom”; “This action will negate the effect of my efforts”

invalidate, nullify

(verb) show to be invalid

invalidate, annul, quash, void, avoid, nullify

(verb) declare invalid; “The contract was annulled”; “void a plea”

Source: WordNet® 3.1

Etymology

Verb

nullify (third-person singular simple present nullifies, present participle nullifying, simple past and past participle nullified)

(transitive, legal) to make legally invalid.

to prevent from happening

Synonyms

• (to make legally invalid): annul, cancel

Source: Wiktionary

Nul"li*fy, v. t. [imp. & p. p. Nullified; p. pr. & vb. n. Nullifying.] Etym: [L. nullificare; nullus none + -ficare (in comp.) to make. See Null, a., and -fy.]

Definition: To make void; to render invalid; to deprive of legal force or efficacy. Such correspondence would at once nullify the conditions of the probationary system. I. Taylor.

Syn.

– To abrogate; revoke; annul; repeal; invalidate; cancel. See Abolish.

Source: Webster’s Unabridged Dictionary 1913 Edition