Un*do" (?), v. t. [AS. undn. See 1st Un-, and Do to perform.]
To reverse, as what has been done; to annul; to bring to naught.
What's done can not be undone.
To-morrow, ere the setting sun,
She 'd all undo that she had done.
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.
Pray you, undo this button.
She took the spindle, and undoing the thread gradually, measured it.
Sir W. Scott.
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,
© Webster 1913.