Nullify

Verb

 * 1)  to make legally invalid.
 * The contract has been nullified.
 * 1) to prevent from happening

Synonyms

 * terminate

Thesaurus
abate, abjure, abolish, abrogate, absolve, annihilate, annul, assert the contrary, belie, bring to naught, bring to nothing, buffer, cancel, cancel out, come to nothing, compensate, confine, contest, contradict, contravene, controvert, counter, counteract, counterbalance, countermand, counterorder, countervail, cross, declare a moratorium, deny, disaffirm, disallow, disannul, disavow, disclaim, disown, disprove, dispute, do away with, forswear, frustrate, gainsay, impugn, invalidate, join issue upon, limit, make void, negate, negativate, negative, neutralize, not accept, not admit, obliterate, offset, oppose, override, overrule, quash, recall, recant, refuse to admit, refute, renege, renounce, repeal, repudiate, rescind, restrict, retract, reverse, revoke, set aside, stultify, suspend, take back, take issue with, thwart, undo, vacate, vitiate, void, waive, wipe out, withdraw, write off

Etymology
null + -ify

Translations

 * Chinese: 使無效, 使无效
 * Dutch: annuleren, vernietigen, ongedaan maken
 * Finnish: mitätöidä
 * French:
 * German:
 * Greek: (akyróno)
 * Italian:
 * Portuguese:
 * Romanian: a anula
 * Russian: аннулировать (annulírovat')
 * Spanish:
 * Swedish: omintetgöra