Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “undo”

undo

verb [T]  /ʌnˈdu/ (present participle undoing, past tense undid  /ʌnˈdɪd/, past participle undone  /ʌnˈdʌn/) us  

undo verb [T] (UNFASTEN)

to unfasten something that is closed or tied: He undid the top button of his shirt and loosened his tie.

undo verb [T] (REMOVE EFFECTS)

to remove the effects of something that happened earlier: It’s difficult to undo the damage caused by a father who abandons his child.
(Definition of undo from the Cambridge Academic Content Dictionary © Cambridge University Press)
What is the pronunciation of undo?
Add Cambridge dictionaries to your browser to your website

Definitions of “undo” in other dictionaries

Word of the Day

beer mat

a small piece of cardboard that you put under a glass to protect a table surface in a pub or bar

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More