Meanings of undoable in English

The error, this simple, stupid, unconscious, un-undoable error, haunts my building even now.

He did the undoable and badmouthed Sam Goldwyn Jr.

But part of the job of a leader on the scene is to discern what's doable from undoable.

We thought the unthinkable; did the undoable; the conventional became a constraint to be unshackled; what was traditional became old-fashioned.

There is no moral obligation to believe what is unbelievable any more than there is a moral obligation to do what is undoable.