UNDO, verb transitive preterit tense undid; participle passive undone.
1. To reverse what has been done; to annul; to bring to naught any transaction. We can undo many kinds of work; but we cannot undo crimes, errors or faults.
Tomorrow ere the setting sun, she'd all undo what she had done.
2. To loose; to open; to take to pieces; to unravel; to unfasten; to untie; as, to undo a knot.
3. To ruin; to bring to poverty; to impoverish. Many are undone by unavoidable losses; but more undo themselves by vices and dissipation, or by indolence.
4. To ruin, in a moral sense; to bring to everlasting destruction and misery.
5. To ruin in reputation.