The Oxford Thesaurus An A-Z Dictionary of Synonyms - undov.

1) loosen, loose, open, unfasten, unhook, unlace, unzip, unsnap, unbutton, untie, unpin; unlock, unbolt: Help me undo my blouse. Don't undo the gate - you'll let the dogs out. 2) unwrap, uncover, open, untie, unbind: Why have you allowed the children to undo their Christmas presents a week early? 3 cancel, annul, rescind, nullify, void, declare null and void, reverse, invalidate: If one could undo things there would be no such thing as regret.