Definition of "irrevocable"

Firm and irrevocable is my doomWhich I have pass'd upon her; she is banish'd.

c. 1598–1600 (date written), William Shakespeare, “As You Like It”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene iii]

I have talked thus to you, child, not to insult you for what is past and irrevocable, but to caution and strengthen you for the future.

1749, Henry Fielding, The History of Tom Jones, a Foundling

On each face, wonder and fear were painted vividly; each so still and silent, looking at the other over the black gulf of the irrevocable past.

1846 October 1 – 1848 April 1, Charles Dickens, chapter 61, in Dombey and Son, London: Bradbury and Evans, […], published 1848

Once again, Mario Cipollini has announced his definite, absolute, unswerving and irrevocable decision to retire, and this time he means it. Probably.

2005 April 28, Samuel Abt, “Cycling: Cipo retires. Definitely. Absolutely. Yes. Probably”, in New York Times, retrieved 27 April 2014