Undo/ʌnˈduː/ Definition 1 of 4Pro Tip 1/3Metaphorical Use The term 'undo' can suggest fixing errors, not just computing actions. The new policy might undo years of progress in education. Pro Tip 2/3Time Sensitivity Using 'undo' implies a wish to go back in time and change what happened. If I could, I'd undo what I said yesterday. Pro Tip 3/3Irreversible Actions 'Undo' cannot always be applied; some actions are permanent. Once spoken, harsh words can't be undone.