Irrevocable

[Sarah]

An adjective:
Incapable of being changed or called back.

[Tanya Shivari]

Unalterable; unable to be [undone]
[That word] on the back of the first Twilight novel that [nobody knows] how to pronounce, or is really sure of what it means

[Zipporah Schumaker]

Not able to be changed, reversed, or recovered; final.

[Jason Yan]

impossible to change:

[Greta]

incapable of being retracted or revoked

[Merna]

Unable to be retracted or reversed. Final.

[engladNak]

Not to be recalled; not to be brought back; not to be reversed.

[MashaDit]

ir-rev′o-ka-bl, adj. that cannot be recalled.—n. Irrev′ocableness.—adv. Irrev′ocably.