undo
Americanverb (used with object)
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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
- undoable adjective
- undoer noun
Etymology
Origin of undo
First recorded before 900; Middle English; Old English undōn; cognate with Dutch ontdoen; un- 2, do 1
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.
But the judge said he had no authority to undo Essayli’s designation as first assistant.
From Los Angeles Times • Apr. 4, 2026
"No sentence can undo the trauma of what she endured. But we hope today marks the beginning of her journey toward the bright, safe, and happy future she deserves," the judge told the court.
From BBC • Mar. 27, 2026
"And so those two things combined would make me undo what I did in December," Miran said.
From Barron's • Feb. 19, 2026
All of the romance and wistfulness of the concert can’t undo years of heartbreak and resentment.
From Salon • Feb. 5, 2026
It has all been a big mistake—a mistake we cannot undo.
From "Blood on the River" by Elisa Carbone
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.
