Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “undo”

See all translations

undo

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

undo verb [T] (UNFASTEN)

B2 to unfasten something that is fastened or tied: Can someone help me to undo my seat belt?
More examples

undo verb [T] (REMOVE EFFECTS)

B2 to remove the good or bad effects of an action or several actions: I did a really tough aerobics class and then went out for a meal and undid (all) the good work! It's very difficult to undo the damage that's caused by inadequate parenting in a child's early years.
(Definition of undo from the Cambridge Advanced Learners Dictionary & Thesaurus © 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

pup

a baby of particular animals, or a puppy

Word of the Day

I won’t tolerate it! Replacing formal words with phrasal verbs.

by Liz Walter,
April 01, 2015
When you are using a language, it is important to understand if a word is formal or informal, so that you can use it in an appropriate way. You might hear people saying dosh for money, or spud for potato, but they wouldn’t write those words in a formal essay. Similarly, a

Read More 

stackin’ p

March 30, 2015
idiom slang earning a lot of money ‘That’s a very generous present.”Yeah, well, she’s stackin’ p, innit?’

Read More