undo

1 of 2

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

undoer

2 of 2

noun

un·​doer "+ 

: one that undoes : destroyer

especially : one that ruins a woman : seducer

Synonyms of undo

Verb

• paralyze
• scare
• frighten
• intimidate

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

Verb

Unfortunately, many in Congress still oppose reforms — such as the RESTORE Patent Rights Act, the PREVAIL Act, and the Patent Eligibility Restoration Act — that would strengthen America’s IP system and undo the mistakes of recent decades. — Andrei Iancu, Fortune, 20 Oct. 2026

In a post on X, Zelenskyy said that ″the decision to undo all of this, to block all of it, seems wrong to me. — Elsa Ohlen,lim Hui Jie, CNBC, 19 Oct. 2026

That’s the sort of publicity no university wants and no amount of money can undo. — Jens Ludwig, Chicago Tribune, 18 Oct. 2026

Kohberger is attempting to undo his guilty plea in the University of Idaho student murders that killed Madison Mogen, 21, Kaylee Goncalves, 21, Xana Kernodle, 20, and Ethan Chapin, 20, in November 2022. — Michael Ruiz, FOXNews.com, 16 Oct. 2026

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

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