Invalidate

v. t.

1.

To render invalid; to weaken or lessen the force of; to destroy the authority of; to render of no force or effect; to overthrow; as, to invalidate an agreement or argument. [imp. & p. p. Invalidated ; p. pr. & vb. n. Invalidating.]

Verb	1.	invalidate - declare invalid; "The contract was annulled"; "void a plea" Synonyms: annul, nullify, void, quash, avoid Antonyms: validate, formalise, formalize - declare or make legally valid
	2.	invalidate - of cheques or tickets Synonyms: cancel
	3.	invalidate - show to be invalid Synonyms: nullify Antonyms: validate - prove valid; show or confirm the validity of something
	4.	invalidate - take away the legal force of or render ineffective; "invalidateas a contract" Synonyms: vitiate, void Antonyms: validate - make valid or confirm the validity of; "validate a ticket"

abate, abrogate, annihilate, belie, blow sky-high, blow up, bring to naught, bring to nothing, buffer, cancel out, come to nothing, counterbalance, countermand, counterorder, deflate, disannul, disconfirm, discredit, disprove, disqualify, do away with, explode, expose, frustrate, make void, negate, negativate, negative, neutralize, nullify, offset, override, overrule, prove the contrary, puncture, quash, recall, recant, renege, repeal, rescind, retract, reverse, set aside, show up, stultify, suspend, thwart, undercut, undo, unfit, vacate, vitiate, void, waive, withdraw, write off