irreversible

UK: /ˌɪrɪˈvɜː^rsɪb^əl/ US: /ˌɪrɪˈvɝsəbəl/ ,(ir′i vûr′sə bəl)

WordReference Random House Learner's Dictionary of American English © 2026

ir•re•vers•i•ble /ˌɪrɪˈvɜrsəbəl/   adj. 

1. not reversible;
   that cannot be changed:
   His refusal is irreversible.

ir•re•vers•i•bly, adv.: 

He is irreversibly opposed to your nomination.

See -vert-.

WordReference Random House Unabridged Dictionary of American English © 2026

ir•re•vers•i•ble  (ir′i vûr′sə bəl), adj. 

1. not reversible;
   incapable of being changed:
   His refusal is irreversible.

• ir-² + reversible 1620–30

ir′re•vers′i•bil′i•ty, ir′re•vers′i•ble•ness, n. 
ir′re•vers′i•bly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

irreversible / ˌɪrɪˈvɜːsəb^əl/ adjective

1. not able to be reversed: the irreversible flow of time
2. not able to be revoked or repealed; irrevocable
3. capable of changing or producing a change in one direction only: an irreversible reaction

ˌirreˌversiˈbility, ˌirreˈversibleness noun

ˌirreˈversibly adverb