Definition of undo
undidplay \ˌən-ˈdid, ˈən-\;
undoneplay \ˌən-ˈdən, ˈən-\;
undoingplay \ˌən-ˈdü-iŋ, ˈən-\
1 : to open or loose by releasing a fastening
2 : to make of no effect or as if not done : make null : reverse
: to come open or apart
undoerplay \ˌən-ˈdü-ər, ˈən-\ noun
Examples of undo in a sentence
You can't undo the past.
The damage cannot be undone.
He was undone by greed.
Before 12th Century
First Known Use of undo
before 12th century
UNDO Defined for English Language Learners
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
Definition of undo for Students
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).