undo

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-

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
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

intransitive verb

: to come open or apart
undoer noun

Examples of undo in a Sentence

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.
Administration officials at all levels say the push to undo Medicaid cuts Republicans passed this summer amounts to providing health care to undocumented immigrants. Franco Ordoñez, NPR, 2 Oct. 2025 If the second cornerback spot becomes a liability, plays like the one just described can quickly and detrimentally be undone. Brooks Kubena, New York Times, 1 Oct. 2025 Netanyahu knows that his political future is dependent on keeping far-right members of his coalition on board – and that dynamic has undone past pushes for the end of the war. Asher Kaufman, The Conversation, 30 Sep. 2025 Yet no less worthy are the moments of self-correction, when a thinker dares to undo what once seemed certain. Shai Tubali, Big Think, 30 Sep. 2025 See All Example Sentences for undo

Word History

First Known Use

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

Browse Nearby Words

Cite this Entry

“Undo.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undo. Accessed 7 Oct. 2025.

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

Last Updated: - Updated example sentences
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