Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

  

English definition of “undo”

undo

verb [T]     /ʌnˈduː/ (present participle undoing, past tense undid, past participle undone)
OPEN B2 to open something that is tied or fastened : I took off my hat and undid my coat . Can you undo this knot for me?Unfastening and opening
GET RID OF EFFECTS B2 to get rid of the effects of something that has been done before: Some of the damage caused by pollution cannot be undone.Removing and getting rid of thingsTaking things away from someone or somewhere
(Definition of undo verb from the Cambridge Learner's Dictionary © Cambridge University Press)

Definitions of “undo” in other dictionaries

Word of the Day

tie the knot

to get married

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