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 court sentence can undo the suffering that has been caused or restore all that each person has lost."
From BBC ● Oct. 7, 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
Their stalemate heated up this summer, when a fresh appeal seeking to undo the agreement reached the 9th Circuit.
From Los Angeles Times ● Aug. 19, 2026
“It lets you check the contents without having to undo the zipper.”
From "A Walk in the Woods" by Bill Bryson
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 Malibu property, listed at $39 million, is in the midst of renovation as its new owner undoes Ye’s head-scratching remodeling choices.
From Los Angeles Times ● Jul. 3, 2025
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
But it does no good, undoes no spell.
From "The Cruel Prince" by Holly Black
There was plenty to like about reaching Q3 in the Audi, but the race undid that good work.
From BBC ● Oct. 4, 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
Collette, who has two teenage children and lives in Sydney, discusses the altar she keeps at home, the power of birth order and the mohair sweater that nearly undid her.
From The Wall Street Journal ● Dec. 15, 2025
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
She did and undid this in every class she attended, six times a day.
From "Stargirl" by Jerry Spinelli
Arsenal had performed reasonably well against City, took the lead twice and were ultimately undone by small margins.
From BBC ● Oct. 4, 2026
Here are four mistakes that generally can’t be undone and how to avoid them:
From The Wall Street Journal ● Sep. 29, 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
Andrews said she is glad the report looked comprehensively at these issues, but given how many recommendations were made and how much was left undone after the Woolsey fire, it’s “not reassuring,” she said.
From Los Angeles Times ● Sep. 15, 2026
And whatever decision he’s just made about me can’t be undone.
From "Dumplin'" by Julie Murphy
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
And in its zeal to purge the newsroom of dissent, CBS and Weiss may have inadvertently triggered the creation of their most dangerous future competitor — and accidentally set the stage for its own undoing.
From Salon ● Aug. 8, 2026
A spell has erased Peter Parker from the world’s memory — the price of undoing the public exposure of his identity — leaving him a stranger to his best friend, Ned, and to MJ.
From Los Angeles Times ● Jul. 30, 2026
“Try again,” my instructor said, after undoing my mess.
From The Wall Street Journal ● Jul. 5, 2026
Somehow I had always felt the tannery would eventually be our undoing.
From "Nectar in a Sieve" by Kamala Markandaya
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.
