Meaning of “undo” in the English Dictionary

"undo" in British English

See all translations

undoverb [ T ]

uk /ʌnˈduː/ us /ʌnˈduː/ present participle undoing, past tense undid, past participle undone

undo verb [ T ] (UNFASTEN)

B2 to unfasten something that is fastened or tied:

Can someone help me to undo my seat belt?

More examples

  • I undid the buttons on my blouse.
  • He had eaten so much that he had to undo his belt a couple of notches.
  • He had undone the buttons of his shirt, exposing an unsightly expanse of white flesh.
  • If the curtains are too short you could undo the hem to make them a bit longer.
  • He gently began to undo the zip at the back of her dress.

(Definition of “undo” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)

"undo" in American English

See all translations

undoverb [ T ]

us /ʌnˈdu/ present participle undoing, past tense undid /ʌnˈdɪd/ , past participle undone /ʌnˈdʌn/

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)