undo

undo — verb

1. to release or separate something that has been closed, tied, or fastened — like

1.verbtransitiveB1
Definition

to release or separate something that has been closed, tied, or fastened — like untying a shoelace, unbuttoning a shirt, or unzipping a jacket.

Example

Yasmin carefully undid the knot in her necklace chain with her fingernails.

undo + concrete physical object (knot)

The toddler undid every button on his shirt before his mother could stop him.

Common collocations
  • undo a knot
  • undo a button
  • undo a zipper
  • undo a shoelace
  • undo a buckle
Synonyms
  • unfasten

    more formal and general; works for any kind of fastening

  • untie

    specific to knots, laces, or ribbons

  • loosen

    suggests making less tight rather than fully opening

  • unbutton

    specific to buttons only

Antonyms
  • fasten

    general opposite — to close or fix something in position

  • tie

    specific to laces, ropes, or ribbons

Grammar Patterns

undo + noun phrase (concrete object: button, knot, shoelace, zipper)

Usage Note

Object is always a concrete fastening device (button, knot, zipper, lace, buckle, tie) or a garment that has such a fastening. Not used for opening a container by lifting a lid or pulling a tab — use 'open' for those.

Common Mistakes

She undid the box to find her phone.
She opened the box to find her phone.
undo means releasing a fastening, not opening a lid or flap.
He undid the bottle by twisting the cap.
He opened the bottle by twisting the cap.
undo only applies to fastenings like buttons, knots, ties, or zippers.

2. to cancel or roll back whatever happened as a result of something someone did, b

2.verbtransitiveB1
Definition

to cancel or roll back whatever happened as a result of something someone did, bringing things back to how they were earlier — for example, cancelling a change on a computer or making up for harm done in a relationship.

Example

Inês knew that no apology could undo the hurt caused by her unkind words.

undo + abstract noun (hurt, damage, effect)

Christopher panicked when he realised he could not undo the message he had just sent.

Common collocations
  • undo the damage
  • undo a mistake
  • undo a change
  • undo the harm
  • undo the effects
Synonyms
  • reverse

    more formal; often used in technical or legal contexts

  • cancel

    focuses on preventing the effect from continuing

  • nullify

    formal; suggests making something legally or officially void

  • rectify

    formal; implies correcting an error or problem

Antonyms
  • cause

    to make something happen, the opposite of reversing an effect

  • do

    the general verb for performing an action that might later be undone

Grammar Patterns

undo + noun phrase (abstract effect, action, or change)

Usage Note

Object is usually an abstract noun describing the consequence of an action (damage, harm, change, mistake, effect). In computing, 'undo' is a standard command and the object can be the action itself (undo a deletion, undo a change).

Common Mistakes

I undid the document from my computer.
I deleted the document from my computer.
undo reverses an action; delete removes an object.
She undid the meeting.
She cancelled the meeting.
undo is for reversing effects, not cancelling scheduled events.

3. to cause the failure, collapse, or destruction of a person, plan, organisation,

3.verbtransitiveB2
Definition

to cause the failure, collapse, or destruction of a person, plan, organisation, or situation, often through a series of actions or a single decisive event.

Example

A single scandal undid twenty years of progress for the environmental group.

undo + abstract noun (progress, career, plans — cause ruin)

Wren's poor business decisions eventually undid everything her parents had built over decades.

Common collocations
  • undo someone's progress
  • undo a career
  • undo a plan
  • undo an organisation
Synonyms
  • ruin

    more direct and common; suggests complete destruction

  • wreck

    stronger; implies violent or total destruction

  • sabotage

    implies deliberate harm, often secret or underhanded

  • destroy

    general; can apply to physical or abstract things

Antonyms
  • build

    to construct or develop over time

  • strengthen

    to make something stronger, the opposite of causing failure

Grammar Patterns

undo + noun phrase (person, plan, career, organisation)

Usage Note

The object is always something that was built up over time (reputation, career, progress, fortune, plans). This sense carries a strong implication of a fall from a previous good state. Distinguish from sense 2 by noting that sense 2 is about reversing an effect (which could be neutral), while sense 3 is specifically about causing catastrophic failure or destruction.

Common Mistakes

The storm undid the roof of the house.
The storm destroyed the roof of the house.
undo in this sense applies to abstract collapse (career, plans, reputation), not physical destruction.
His laziness undid his homework.
His laziness undid his chances of passing the class.
undo (sense 3) means destroying long-term progress, not simply failing to complete a single task.
Phrasal verbs

come undone

phrasal verb

1. (physical) to become unfastened or untied. 2. (figurative) to fail or fall apart, especially after a period of apparent success or stability.

Yara noticed her shoelace had come undone, so she knelt down and retied it.

The team's perfect season came undone when their star player got injured.

Word family

  • undoing
    nounB2
  • undone
    adjectiveB1
  • re-undo
    verb
  • undoable
    adjectiveC1

Synonym discussion

Sense: verb/2

These verbs all describe making something ineffective, but they differ in scope and formality. 'Undo' is the most general, everyday word — you can undo a typo, undo damage, or undo a change on a computer. 'Reverse' is more formal and often implies a deliberate change of direction (reverse a decision, reverse a policy). 'Cancel' focuses on preventing something from continuing or taking effect (cancel a subscription, cancel a flight). 'Nullify' is formal and legal — it means to make something officially void (nullify a contract, nullify a vote). 'Rectify' carries a sense of correcting a wrong or error (rectify a mistake, rectify an injustice). In daily conversation, 'undo' is the simplest choice for most situations, while the others are useful in formal writing or specific technical domains.

undo ↗reverse ↗cancel ↗nullifyrectify

Common collocations

Nouns

Adverbs

Phrases

Etymology

Old EnglishMiddle EnglishModern English

From Old English 'undōn', a combination of the prefix 'un-' (meaning 'reverse' or 'opposite of') and 'dōn' (meaning 'to do'). So the original meaning was literally 'to reverse doing' — to take back or cancel something that has been done. The sense of physically unfastening emerged in early Middle English, and the sense of causing ruin developed later in the 16th century.