Un‐do″ (?), v. t. [AS. und�n. See 1st Un-, and Do to perform.] 1. To reverse, as what has been done; to annul; to bring to naught.
What's done can not be undone. Shak.
To-morrow, ere the setting sun,
She 'd all undo that she had done. Swift.
2. To loose; to open; to take to piece; to unfasten; to untie; hence, to unravel; to solve; as, to undo a knot; to undo a puzzling question; to undo a riddle. Tennyson.
Pray you, undo this button. Shak.
She took the spindle, and undoing the thread gradually, measured it. Sir W. Scott.
3. To bring to poverty; to impoverish; to ruin, as in reputation, morals, hopes, or the like; as, many are undone by unavoidable losses, but more undo themselves by vices and dissipation, or by indolence.
That quaffing and drinking will undo you, Shak.