Undo

//ʌnˈduː// adj, noun, verb, slang

adj, noun, verb, slang ·Common ·Middle school level

Definitions

Noun
  1. 1
    An operation that reverses a previous action. transitive

    "How many undos does this program support?"

Verb
  1. 1
    To reverse the effects of an action. transitive

    "Fortunately, we can undo most of the damage to the system by the war."

  2. 2
    remove the outer cover or wrapping of wordnet
  3. 3
    To unfasten. transitive

    "Could you undo my buckle for me?"

  4. 4
    cause to become loose wordnet
  5. 5
    To unfasten the clothing of (a person). colloquial, transitive

    "PROSTITUTE: Undo me. There's a dear."

Show 4 more definitions
  1. 6
    cancel, annul, or reverse an action or its effect wordnet
  2. 7
    To impoverish or ruin, as in reputation; to cause the downfall of. figuratively, transitive

    "Woe is me, for I am undone!"

  3. 8
    deprive of certain characteristics wordnet
  4. 9
    cause the ruin or downfall of wordnet
Adjective
  1. 1
    Misspelling of undue. alt-of, misspelling, transitive

Synonyms

All synonyms
cancelunbuckleunmakeuntieuntieunwrap

Example

More examples

"You cannot undo what has already been done."

Etymology

From Middle English undōn, from Old English ondōn, from Proto-West Germanic *andadōn (“to undo”), equivalent to un- + do. Cognate with West Frisian ûndwaan, ûntdwaan (“to undo; rid”), Dutch ontdoen (“to undo”).

Related phrases

what's done cannot be undone

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.