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

Letting those credits expire would undo years of progress. —Linda Goler Blount, MSNBC Newsweek, 31 Oct. 2025

Nearly every panel of the shoe is tattered and torn, including a heel seam that’s coming undone and reveals the inner cork components of the shoe. —Riley Jones, Footwear News, 30 Oct. 2025

In Virginia, the chapter has not taken a position on Democrats’ effort to undo the commission. —David Weigel, semafor.com, 29 Oct. 2025

The House approved House Bill 491, meant to cover about $190 million in funding needs and undo the new rate reductions. —Nora O'Neill, Charlotte Observer, 27 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