undo

verb
un·​do | \ ˌən-ˈdü, ˈən-\
undid\ ˌən-​ˈdid , ˈən-​ \; undone\ ˌən-​ˈdən , ˈən-​ \; undoing\ ˌən-​ˈdü-​iŋ , 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

Keep scrolling for more

Other Words from undo

undoer \ ˌən-​ˈdü-​ər , ˈən-​ \ noun

Synonyms & Antonyms for undo

Synonyms

demoralize, emasculate, paralyze, unman, unnerve, unstring

Antonyms

nerve

Visit the Thesaurus for More 

Examples of undo in a Sentence

You can't undo the past. The damage cannot be undone. He was undone by greed.
See More

Recent Examples on the Web

Zinke worked to drastically weaken environmental protections The Trump administration has also made point of undoing environmental regulations and Zinke has presided over some of its most impactful rollbacks. Umair Irfan, Vox, "Ryan Zinke to resign as Interior Secretary at the end of the year," 15 Dec. 2018 If consumers stop paying their bills for three consecutive months from the accounts linked to Experian Boost, the company will delete that account from its credit report, which could undo the credit score increase. Annamaria Andriotis, WSJ, "Want a Better Credit Score? Soon, Your Cellphone Bill Could Help," 18 Dec. 2018 The whole effect is a kind of artfully undone St. Bart’s-meets-classic California bungalow style. Andrea Bennett, Condé Nast Traveler, "First Look: Hotel Joaquin in Laguna Beach, California," 30 Nov. 2018 The work of undoing homophobia and transphobia belongs first and foremost to cisgender, heterosexual people. Casey Johnston, SELF, "Ask a Swole Woman: How Can I Find Safe and Inclusive Gyms?," 23 Oct. 2018 There’s no way to know if the lull in eruptions since August is a temporary pause or a more permanent shutdown of the volcano, so park workers are faced with the possibility that a new earthquake or explosion could undo all their work. Avery Thompson, Popular Mechanics, "Hawaii's Volcano National Park, Closed by Kilauea, Is Finally Reopening," 21 Sep. 2018 Yet, the potential for a full-blown trade war risks undoing much of that great work and punishing the very voters who elected him. Tory Newmyer, Washington Post, "The Finance 202: Mnuchin is in denial about the pain Trump's tariffs are inducing," 13 July 2018 At last year’s election the party lost support in metropolitan areas, undoing a decade of patient work by David Cameron to woo socially liberal voters. The Economist, "A culture war comes to Westminster," 5 July 2018 That meant any establishment selling food to-go — as the vast majority of barbecue restaurants do — had to follow the scale laws and regulations, essentially undoing the new law. Andrea Zelinski, San Antonio Express-News, "Texas Ag commissioner, BBQ pitmasters battle over a weighty issue," 3 July 2018

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.

See More

First Known Use of undo

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

Keep scrolling for more

Learn More about undo

Dictionary Entries near undo

undivined

undivinely

undivulged

undo

undoable

undocile

undock

Statistics for undo

Last Updated

14 Jan 2019

Look-up Popularity

Time Traveler for undo

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

See more words from the same century

Keep scrolling for more

More Definitions for undo

undo

verb

English Language Learners Definition of undo

: to open or release (something) : to unfasten or loosen (something)

: to change or stop the effect of (something)

: to cause the failure of (someone or something)

undo

verb
un·​do | \ ˌən-ˈdü \
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.

Keep scrolling for more

More from Merriam-Webster on undo

Rhyming Dictionary: Words that rhyme with undo

Thesaurus: All synonyms and antonyms for undo

Spanish Central: Translation of undo

Nglish: Translation of undo for Spanish Speakers

Britannica English: Translation of undo for Arabic Speakers

Comments on undo

What made you want to look up undo? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

means, resources, or money

Get Word of the Day daily email!

Test Your Vocabulary

Homophone Quiz

  • three-bears-two-of-them-look-like-theyre-whispering-to-a-third-bear-who-looks-chuffed-to-be-the-center-of-attention
  • In order to judge how people felt, the senator's office hired a firm to take a ______.
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!