ENGLISH
REFERENCE

undo

v.
B1 Intermediate US //ənˈdu// UK //ʌndˈuː// un·do Informal

v. to cancel the last thing you did on a computer or to open something that is tied or fastened.

v. to reverse the effects of a previous action or to unfasten a physical connection. In a digital context, it refers to a command that restores a document to its state prior to the most recent modification.


SIMPLE

I made a mistake, so I clicked undo.

CONTEXTUAL

If you accidentally delete a paragraph, you can usually undo the action by pressing a shortcut on your keyboard.

COMPLEX

The software allows users to undo multiple consecutive actions, providing a safety net for complex design tasks where a single error could compromise the entire project.

Synonyms
Antonyms
Origin

From Middle English undōn, from Old English ondōn, from Proto-West Germanic *andadōn (“to undo”), equivalent to un- + do. Cognate with West Frisian ûndwaan, ûntdwaan (“to undo; rid”), Dutch ontdoen (“to undo”).

Usage

The verb is transitive and requires a direct object, though in computing contexts the object is often implied.

Pitfall

I want to un-do my mistake.I want to undo my mistake.The word is a standard prefix-root combination and does not require a hyphen.

© 2026 English Reference