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

• demoralize
• emasculate
• paralyze
• unman
• unnerve
• unstring

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

But even a bit of late-season luck wouldn’t undo the hardship of the growing season. —Christine Condon, Baltimore Sun, 29 Nov. 2024

Opponents maintain concerns about ultimate choices that can never be undone and the danger of manipulation and exploitation from third parties despite the bill's stringent safeguards. —Gus Alexiou, Forbes, 29 Nov. 2024

For me, there is no funk that can’t be undone by a lush bathrobe, a musky candle, and a face mask. —Channing Smith, Glamour, 27 Nov. 2024

Even if these developmental divergences are, in part, the result of toxic elements, removing those elements from the body later on will not undo the physiological or neurological shifts that have already taken place. —Lauren Leffer, Popular Science, 27 Nov. 2024

Word History

First Known Use

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

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