un·​do | \ ˌən-ˈdü How to pronounce undo (audio) , ˈən- \
undid\ ˌən-​ˈdid How to pronounce undid (audio) , ˈən-​ \; undone\ ˌən-​ˈdən How to pronounce undone (audio) , ˈən-​ \; undoing\ ˌən-​ˈdü-​iŋ How to pronounce undoing (audio) , ˈən-​ \

Definition of undo

transitive verb

1 : to open or loose by releasing a fastening
2 : to make of no effect or as if not done : make null : reverse
3a : to ruin the worldly means, reputation, or hopes of a politician undone by scandal
b : to disturb the composure of : upset she's come undone

intransitive verb

: to come open or apart

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Other Words from undo

undoer \ ˌən-​ˈdü-​ər How to pronounce undoer (audio) , ˈən-​ \ noun

Synonyms & Antonyms for undo



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Examples of undo in a Sentence

You can't undo the past. The damage cannot be undone. He was undone by greed.
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Recent Examples on the Web Although the existing Obama-era limits on mercury and other toxic air pollutants remain in effect, the EPA’s finding still will hand legal ammunition to critics seeking to undo them. Amena Saiyid, Bloomberg.com, "Trump Undermines Mercury Curbs in Move That Could End Mandate," 10 May 2020 People are susceptible to illusions—of love, of devotion, of hope—that undo them. Jeremy Lybarger, The New York Review of Books, "The Mordant Fables of Juraj Herz," 20 Apr. 2020 Is their love strong enough to withstand her work making conservative policy and his work undoing it? Arlene Martinez, USA TODAY, "In CA: The deadliest 24 hours, but for workers still out there, relief," 17 Apr. 2020 By the end of his life – 155 years ago this week – the United States had become a different country, fortified by the very crisis that had threatened to undo it. Ted Widmer, Time, "How Lincoln Managed America's Governors to Become a Great National Leader," 17 Apr. 2020 Republicans are asking the high court to undo a federal judge's ruling this week that declined to postpone the election but added six days, to April 13, for people to submit absentee ballots. NBC News, "United to cut flights to Newark, LaGuardia airports," 6 Apr. 2020 Two-thirds of Republicans favor a constitutional amendment undoing it. Nihal Krishan, Washington Examiner, "Ten years later, Citizens United has boosted megadonors more than corporations," 21 Jan. 2020 Congress can pass a new law to override an executive order and future presidents can undo them. Kevin Freking, chicagotribune.com, "Trump derided Obama’s executive orders as ‘power grabs.’ But in each year of his presidency, Trump has surpassed Obama’s total over the same time span.," 19 Oct. 2019 Last year more than 10m couples tied the knot and nearly 4.5m undid it. The Economist, "In China, courts deny women divorces in the name of “social harmony”," 10 Oct. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'undo.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of undo

before the 12th century, in the meaning defined at transitive sense 1

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Time Traveler for undo

Time Traveler

The first known use of undo was before the 12th century

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Statistics for undo

Last Updated

2 Jun 2020

Cite this Entry

“Undo.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undo. Accessed 5 Jun. 2020.

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More Definitions for undo


How to pronounce undo (audio)

English Language Learners Definition of undo

: to open or release (something) : to unfasten or loosen (something)
: to change or stop the effect of (something)
formal : to cause the failure of (someone or something)


un·​do | \ ˌən-ˈdü How to pronounce undo (audio) \
undid\ -​ˈdid \; undone\ -​ˈdən \; undoing\ -​ˈdü-​iŋ \; undoes\ -​ˈdəz \

Kids Definition of undo

1 : untie sense 2, unfasten Can you undo this knot?
2 : to cancel the effect of : reverse The damage cannot be undone.
3 : to cause the ruin or failure of He was undone by greed.

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More from Merriam-Webster on undo

Thesaurus: All synonyms and antonyms for undo

Rhyming Dictionary: Words that rhyme with undo

Spanish Central: Translation of undo

Nglish: Translation of undo for Spanish Speakers

Britannica English: Translation of undo for Arabic Speakers

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