Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

  

undo

 
 
/ʌnˈduː/ verb [T] (present participle undoing, past tense undid, past participle undone)

Definition

OPEN to open something that is tied or fastened: I took off my hat and undid my coat. Can you undo this knot for me?
GET RID OF EFFECTS to get rid of the effects of something that has been done before: Some of the damage caused by pollution cannot be undone.
(Definition of undo verb from the Cambridge Learner's Dictionary © Cambridge University Press)

“undo” in other dictionaries

Word of the Day

be under a cloud

to not be trusted or popular because people think you have done something bad

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