undo

verb

un·​do ˌən-ˈdü 

ˈən-

undid ˌən-ˈdid 

ˈən-

; undone ˌən-ˈdən 

ˈən-

; undoing ˌən-ˈdü-iŋ 

ˈən-

; undoes

ˌən-ˈdəz, 

ˈən-

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 

ˈən-

noun

Synonyms of undo

• 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

Satenstein’s attempt to replace the treasured grail is a cotton iteration that features a similar neckline to the vintage one, but with a clasp that can be done and undone from a traditional keyhole to a sexy almost V-neck. — Irene Kim, Vogue, 6 Oct. 2026

Qrator specifically warns that removing the malware does not undo credentials or tokens that attackers may have already stolen. — Kurt Knutsson, FOXNews.com, 5 Oct. 2026

Trump’s opponents are making plans to undo his changes to the presidency. — Jamie Ross, Washington Post, 5 Oct. 2026

After five shootings in less than a week left at least 46 people dead, South Africa is wrestling with how to tackle a spike in gun crime that threatens to undo recent progress in reducing its notoriously high murder rate. — Nimi Princewill, CNN Money, 2 Oct. 2026

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