undo
Americanverb (used with object)
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undoes,
present (3rd person singular)
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undid,
past
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undone,
past participle
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undoing
present participle
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to reverse the doing of; cause to be as if never done.
Murder once done can never be undone.
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to do away with; erase; efface.
to undo the havoc done by the storm.
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to bring to ruin or disaster; destroy.
In the end his lies undid him.
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to unfasten by releasing.
to undo a gate; to undo a button.
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to untie or loose (a knot, rope, etc.).
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to open (a package, wrapping, etc.).
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Archaic. to explain; interpret.
verb
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(also intr) to untie, unwrap, or open or become untied, unwrapped, etc
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to reverse the effects of
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to cause the downfall of
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obsolete to explain or solve
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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undosimple
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undoessimple
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have undoneperfect
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has undoneperfect
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am undoingprogressive
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are undoingprogressive
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is undoingprogressive
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have been undoingperfect progressive
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has been undoingperfect progressive
Past
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undidsimple
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had undoneperfect
-
was undoingprogressive
-
were undoingprogressive
-
had been undoingperfect progressive
Future
Etymology
Origin of undo
First recorded before 900; Middle English; Old English undōn; cognate with Dutch ontdoen; see origin at un- 2, do 1
Explanation
When you undo something, you make it invalid, like when governments undo treaties they've signed in the past. Another way to undo is simply to open: "I couldn't undo the knot on my sneakers, so I just slipped them off." When we undo something, we cancel out its results, or reverse them. You might try to undo the damage caused by your little sister's baseball, offering to replace your neighbor's broken window. Formally, this verb also means "cause downfall or ruin," so you could say, "His love of power will undo him in the end."
Vocabulary lists containing undo
Commonly Confused Words, List 3
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Commonly Confused Words, List 5
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Commonly Confused Words, List 11
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
“No sentence can undo what his family and fellow deputies have carried for three years. My thoughts remain with them,” Ohlsen said in a statement.
From Los Angeles Times ● Oct. 1, 2026
He said no apology could undo that but the trust would "support women who have been impacted" in any way possible.
From BBC ● Sep. 24, 2026
This would effectively undo the 2025 rate cuts pushed by former Fed Chairman Jerome Powell, and would bring the central bank’s benchmark interest rate to a range of 4.25% to 4.5%.
From MarketWatch ● Sep. 11, 2026
“Maybe they need to look at the Costa del Whatsit and see what the cost is of tourism, because you can’t undo it once it’s done.”
From Slate ● Sep. 8, 2026
“I’m going to undo the tarpaulin,” he said.
From "The Book of Dust: La Belle Sauvage" by Philip Pullman
The two-segment operating model undoes changes made by former chief executive Bernard Looney that were initiated as part of BP’s pivot to lower-carbon sources of energy.
From The Wall Street Journal ● Jun. 9, 2026
The decision undoes a ruling by US District Judge Maame E Frimpong in Los Angeles, who had said that there is a "mountain of evidence" showing the raids were violating the US Constitution.
From BBC ● Sep. 8, 2025
The decision by an 11-judge 9th Circuit panel undoes one made last year by a three-judge panel of the same court.
From Los Angeles Times ● Jun. 10, 2024
Even though Fennell attempts to make the audience sympathize with Oliver, it does not quite land because of the movie's ending that undoes the groundwork that was laid out.
From Salon ● Dec. 2, 2023
Wordlessly, she reaches up to the nape of her neck and undoes the loose bun she wears when cooking.
From "Internment" by Samira Ahmed
The fastest Ferrari driver across the weekend, but two costly penalties undid much of the good work.
From BBC ● Jul. 26, 2026
Pamela Price was recalled in 2024 and replaced by Ursula Jones Dickson, who quickly undid many of Price’s signature policies.
From Los Angeles Times ● May 29, 2026
But her death undid him, and he found his love for Emma reawakened by remorse.
From The Wall Street Journal ● Jan. 16, 2026
More aggressive fine print restrains other follies like the bond portfolio mismatches that undid California-based Silicon Valley Bank two years ago, says Davide Oneglia, director of European and global macro at TS Lombard.
From Barron's ● Oct. 25, 2025
Sensing the group’s anticipation, though not mine in particular, Josn slowly undid the brass clasps and drew out his lute with an air of studied nonchalance.
From "The Name of the Wind" by Patrick Rothfuss
But it ends up with an outcome that feels as sadly inevitable as it is heartbreaking — an ethical knot that cannot be undone.
From Los Angeles Times ● Oct. 9, 2026
“They have destroyed a lot of buildings to build these outposts, and that is something that can’t be undone, but they could easily leave these giant dirt berms where they are.”
From The Wall Street Journal ● Oct. 9, 2026
Cronje was undone when an Indian police wiretap of a bookmaker caught him in discussions about fixing matches.
From BBC ● Oct. 1, 2026
"I understand that my false accusations have caused Mr Carter immense pain, suffering and damage that can never be fully undone."
From Barron's ● Sep. 25, 2026
Because just when things started to come back together, they came undone in a Big Way.
From "Red Kayak" by Priscilla Cummings
Just over two weeks after its release, Stone’s undoing has racked up more than 1.6 million pageviews.
From Salon ● Sep. 18, 2026
The appellate panel voiced serious doubts about undoing the consent decree at oral arguments in June.
From Los Angeles Times ● Aug. 19, 2026
But the success of the scheme has also been its undoing – it's growing rapidly and costing the government too much.
From BBC ● Aug. 12, 2026
“Try again,” my instructor said, after undoing my mess.
From The Wall Street Journal ● Jul. 5, 2026
She turned her attention to Glerk, analyzing the structure of the spell that had enrabbited him, undoing it bit by bit.
From "The Girl Who Drank the Moon" by Kelly Barnhill
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
