All 5 Uses of

irrevocable
in
Atlas Shrugged

But to convict a human being of that practice was a verdict of irrevocable damnation, and he knew that he would not believe it of anyone, so long as the possibility of a doubt remained.†
Chpt 2.4 *

irrevocable = incapable of being undone

He sat slouched casually on the arm of a chair, leaning forward, his forearm across his knees, his hand hanging down idlyand it was the faint smile on his face that gave to his words the deadly sound of the irrevocable: "Why should this seem so startling?†
Chpt 3.1

For one instant, while he felt the muscles of his face cracking into the fraud of a smile, he felt a formless, an almost supernatural terror, as if he sensed again the silent working of some smooth machine, as if he were caught in it, part of it and doing its irrevocable will.†
Chpt 3.3

There, she thought, was the ultimate goal of all that loose academic prattle which businessmen had ignored for years, the goal of all the slipshod definitions, the sloppy generalities, the soupy abstractions, all claiming that obedience to objective reality is the same as obedience to the State, that there is no difference between a law of nature and a bureaucrat's directive, that a hungry man is not free, that man must be released from the tyranny of food, shelter and clothing-all of it, for years, that the day might come when Nat Taggart, the realist, would be asked to consider the will of Cuffy Meigs as a fact of nature, irrevocable and absolute like steel, rails and gravitation, to accep†
Chpt 3.5