What does "undo" mean?

1. (to reverse an action) to cancel the effect of something that was done before. 2. (to unfasten) to open something that is tied, buttoned, or zipped. 3. (to cause ruin) to cause someone to fail or lose their reputation. 4. (computing command) a button or command that cancels the last thing you did on a computer.

Is it correct to say "I need to unfasten my shoes."?

No — say "I need to undo my shoelaces.". While 'unfasten' is correct, 'undo' is the more natural choice for shoelaces, buttons, and knots.

undo

v. · n.

US //ənˈdu// UK //ʌndˈuː// un·do

Irregular verb past undid past participle undone

1 to reverse an action (v.)
B1 Intermediate

to cancel the effect of something that was done before.

to reverse the effects or consequences of a previous action or decision.

Example

It is difficult to undo the damage caused by a bad reputation.

Example

The new administration sought to undo several of the previous government's most controversial environmental policies within its first hundred days.
- do
- enact
2 to unfasten (v.)
B1 Intermediate

to open something that is tied, buttoned, or zipped.

to unfasten, untie, or loosen a physical connection or closure.

Example

He had to undo his seatbelt before he could get out of the car.

Example

She struggled to undo the intricate silk knots on the parcel without tearing the delicate decorative paper.
- untie
- unfasten
- loosen
Pitfall

I need to unfasten my shoes.

I need to undo my shoelaces.

While 'unfasten' is correct, 'undo' is the more natural choice for shoelaces, buttons, and knots.

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3 to cause ruin (v.)
C1 Advanced Literary

to cause someone to fail or lose their reputation.

to bring to ruin or destruction; to cause the downfall of a person or entity.

Example

His greed would eventually undo him and his entire family.

Example

It was ultimately his stubborn refusal to listen to his advisors that would undo his long and otherwise successful career in diplomacy.
- save
- establish
4 computing command (n.)
B1 Intermediate Computing

a button or command that cancels the last thing you did on a computer.

a function within a software application that reverses the most recent operation and restores the document to its previous state.

Example

If you make a mistake while typing, just click undo.

Example

The application supports multiple levels of undo, allowing the designer to revert through several hours of incremental changes if necessary.
- reversal
- redo

Origin

From Middle English undōn, from Old English ondōn, from Proto-West Germanic *andadōn (“to undo”), equivalent to un- + do. Cognate with West Frisian ûndwaan, ûntdwaan (“to undo; rid”), Dutch ontdoen (“to undo”).