undo

verb

un·​do ˌən-ˈdü 

ˈən-

undid ˌən-ˈdid 

ˈən-

; undone ˌən-ˈdən 

ˈən-

; undoing ˌən-ˈdü-iŋ 

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

c

: seduce sense 3

intransitive verb

: to come open or apart

undoer

ˌən-ˈdü-ər 

ˈən-

noun

Synonyms

• paralyze
• scare
• frighten
• intimidate

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

Courts undid Nixon’s actions, and Congress eventually passed the Impoundment Control Act of 1974, which outlawed the maneuver, leaving only narrow exceptions—rescissions—that required congressional sign-off. —Andy Kroll, New Yorker, 17 Oct. 2025

Washington’s roster has been ravaged by injuries this season, essentially undoing many of Peters’ offseason moves. —Nicki Jhabvala, New York Times, 17 Oct. 2025

But when the French themselves started to undo abolition, Dessalines understood that freedom could be preserved only with independence. —Julia Gaffield, The Conversation, 15 Oct. 2025

Another round of tit-for-tat tariffs would undo the progress made during months of meetings between Chinese and US officials. —Auzinea Bacon, CNN Money, 12 Oct. 2025

Word History

First Known Use

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

Rhymes for undo

• accrue
• ado
• ainu
• aircrew
• airscrew
• anew
• askew
• baboo
• babu
• bamboo
• beaucoup
• bijou

Kids Definition

undo

verb

un·​do ˌən-ˈdü 

ˈən-

undid -ˈdid  ; undone -ˈdən  ; undoing -ˈdü-iŋ 

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