Webster's Revised Unabridged Dictionary · 1913

Undo

Undo , transitive verb

[Anglo-Saxon und{not transcribed}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. — Shakespeare
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. — Shakespeare
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, — Shakespeare