undo

The word “undo” means to reverse or cancel the effect of something already done. In plain terms, to reverse something — put it back the way it was, unfasten it, or ruin it.

“Undo” is pronounced uhn-DOO (/ʌnˈduː/ in IPA).

Here is “undo” used in a sentence: “It took years to undo the damage caused by the flood.”

The opposite of “undo” — its antonyms — are redo, do up, button, button up and tie up.

Depending on how it is used, “undo” can be a verb and a noun.

The word “undo” comes from Old English. From Old English ondōn, from a Germanic root meaning "to do the opposite of" — un- plus do.

“Undo” is an uncommon word in modern English, usually learned at around the B1 level.

“Undo” has 4 distinct senses listed in this dictionary. The most common is: to reverse or cancel the effect of something already done.

Undo reverses a previous action so things return to how they were before, while delete permanently removes something without restoring any prior state. In software, undo is typically reversible again through redo, whereas delete usually is not unless a separate recovery feature exists.

As a verb, undo means to reverse an action or unfasten something, as in 'undo the damage' or 'undo your zip.' As a noun, undo (or 'the undo') refers to the command or feature itself, such as clicking undo in a word processor.

A frequent error is confusing undo with 'undue,' which is an unrelated word meaning excessive or inappropriate. Undo always relates to reversing an action, fastening, or downfall, while undue describes something unwarranted.