invalidate

UK: /ɪnˈvælɪdeɪt/ US: /ɪnˈvælɪˌdeɪt/ ,(in val′i dāt′)

Inflections of 'invalidate' (v): (⇒ conjugate)

invalidates

v 3rd person singular

invalidating

v pres p

invalidated

v past

invalidated

v past p

WordReference Random House Learner's Dictionary of American English © 2025

in•val•i•date /ɪnˈvælɪˌdeɪt/   v. [~ + object] , -dat•ed, -dat•ing. 

1. to discredit; show that (something) is incorrect:
   This new finding invalidates his previous argument.
2. to deprive of legal force;
   nullify:
   The judge invalidated the guilty verdict and set the defendant free.

in•val•i•da•tion /ɪnˌvælɪˈdeɪʃən/  n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

in•val•i•date  (in val′i dāt′), v.t., -dat•ed, -dat•ing. 

1. to render invalid;
   discredit.
2. to deprive of legal force or efficacy;
   nullify.

• invalid² + -ate¹ 1640–50

in•val′i•da′tion, n. 
in•val′i•da′tor, n. 
Synonyms

• 1. weaken, impair; disprove, refute, rebut.

Collins Concise English Dictionary © HarperCollins Publishers::

invalidate / ɪnˈvælɪˌdeɪt/ verb (transitive)

1. to render weak or ineffective, as an argument
2. to take away the legal force or effectiveness of; annul, as a contract

inˌvaliˈdation noun

inˈvaliˌdator noun