undo

1 of 2

verb

un·​do ˌən-ˈdü How to pronounce undo (audio)
ˈən-
undid ˌən-ˈdid How to pronounce undo (audio)
ˈən-
 ; undone ˌən-ˈdən How to pronounce undo (audio)
ˈən-
 ; undoing ˌən-ˈdü-iŋ How to pronounce undo (audio)
ˈən-
 ; undoes
ˌən-ˈdəz, 
ˈən-
Synonyms of undonext

transitive verb

1
: to open or loosen by releasing a fastening
undid her jacket
2
: to make of no effect or as if not done : make null : reverse
The damage cannot be undone.
3
a
: 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
c
: seduce sense 3

intransitive verb

: to come open or apart
undoer
ˌən-ˈdü-ər How to pronounce undo (audio)
ˈən-
noun

undoer

2 of 2

noun

un·​doer "+ How to pronounce undoer (audio)
: one that undoes : destroyer
especially : one that ruins a woman : seducer

Synonyms of undo

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Verb

See All Synonyms & Antonyms in Thesaurus

Examples of undo in a Sentence

Verb You can't undo the past. The damage cannot be undone. He was undone by greed.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Verb
And then the movie kind of became about undoing that. — Adriane Quinlan, Curbed, 28 June 2026 Well, Ariana seems to remember, whereas Hudson is determined to just undo the breakup and pretend like none of it ever happened. — Tom Smyth, Vulture, 2 July 2026 Wall Street analysts also lament his stance on forward guidance (or lack thereof), saying its reduction undoes transparency at the central bank. — Eleanor Pringle, Fortune, 3 July 2026 Sitting on the Same Edge Every Day Rotating your mattress regularly aims to prevent uneven wear—but your morning routine might be undoing that effort. — Jamie Cuccinelli, Martha Stewart, 1 July 2026 See All Example Sentences for undo

Word History

Etymology

Noun

Middle English, from undon to undo + -er

First Known Use

Verb

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

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

Rhymes for undo

See All Rhymes for undo

Browse Nearby Words

undivulged
undo
undoable
See all Nearby Words

Cite this Entry

“Undo.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undo. Accessed 7 Jul. 2026.

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Kids Definition

undo

verb
un·​do ˌən-ˈdü How to pronounce undo (audio)
ˈən-
undid -ˈdid How to pronounce undo (audio) ; undone -ˈdən How to pronounce undo (audio) ; undoing -ˈdü-iŋ How to pronounce undo (audio)
1
: to make or become unfastened or loosened : open, untie
undo a knot
2
: to destroy the effect of : nullify, reverse
3
a
: to cause the ruin of
your stubbornness undid you
undone by greed
b
: to disturb the calmness of : upset
she's come undone
undoer noun

More from Merriam-Webster on undo

Nglish: Translation of undo for Spanish Speakers

Last Updated: - Updated example sentences
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