undo

play
verb un·do \ ˌən-ˈdü , ˈən- \

Definition of undo

undid play \ˌən-ˈdid, ˈən-\; undone play \ˌən-ˈdən, ˈən-\; undoing play \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 3
intransitive verb
:to come open or apart

undoer

play \ˌən-ˈdü-ər, ˈən-\ noun

Examples of undo in a Sentence

  1. You can't undo the past.

  2. The damage cannot be undone.

  3. He was undone by greed.

Recent Examples of undo from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'undo.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of undo

before 12th century


UNDO Defined for English Language Learners

undo

play
verb

Definition of undo for English Language Learners

  • : to open or release (something) : to unfasten or loosen (something)

  • : to change or stop the effect of (something)

  • : to cause the failure of (someone or something)


UNDO Defined for Kids

undo

play
verb un·do \ ˌən-ˈdü \

Definition of undo for Students

undid \-ˈdid\; undone \-ˈdən\; undoing \-ˈdü-iŋ\; undoes \-ˈdəz\
1 :untie 2, unfasten
  • Can you undo this knot?
2 :to cancel the effect of :reverse
  • The damage cannot be undone.
3 :to cause the ruin or failure of
  • He was undone by greed.


Seen and Heard

What made you want to look up undo? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

all at once

Get Word of the Day daily email!

Test Your Vocabulary

Challenging Vocabulary Quiz Returns!

  • stylized-drawing-of-woman-pole-vaulting-across-gap-to-get-trophy
  • Which is a synonym of fuliginous?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!