The verb to undo · Conjugation
Past Simple of undo
The answer: undid
A2
A finished action at a definite time in the past.
Quick answer
The Past Simple of the verb to undo is undid.
Example: He undid the knot.
Full conjugation in the Past Simple
| Pronoun | Form |
|---|---|
| I | undid |
| You | undid |
| He / She / It | undid |
| We | undid |
| You (pl.) | undid |
| They | undid |
Common mistakes to avoid
1. He undoed the knot ❌
Undo follows do → did → done: He undid the knot.
2. Undone = open or not done
Undone means open, cancelled or not done: My laces are undone. For something that you cannot change, use done: What's done is done (you can't go back).
Practice quiz
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Frequently asked questions
What is the past tense of undo?+
The Past Simple is undid, and the past participle is undone. It follows do → did → done (undo = un + do).
What is the shortcut for undo?+
Undo cancels your last action: Ctrl+Z (Windows) or Cmd+Z (Mac). You find it in almost every program.
What is the meaning of what's done is done?+
It is a saying: what has happened cannot be changed, so you cannot undo it. It is about accepting things that you can't change.
Can you undo a button?+
Yes. Undo a button means to open it on a piece of clothing. For a knot, you can say undo a knot or untie a knot.
Is undoed a word?+
No. Undo = un + do, and it follows the irregular verb do: undid, undone.
Related pages: undo Past Simple
Pages on a similar topic or with a similar use, so you can keep exploring.
Updated on 12 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 12 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/verbs/undo/past-simple
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.
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More forms of the verb to undo are coming soon.