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Set off meaning

Set off means to start a journey. It can also mean to make an alarm ring or a bomb or fireworks explode.

Check yourself: 3 questions

set off

set off · set · setting

B1No object+2 more meanings

We set off early to miss the traffic.

Set off meanings and examples

3 meanings, each with its own CEFR level. A level marked ~ is our estimate: Oxford and Cambridge give none for that meaning.

  1. 1start a journey
  2. 2make an alarm ring or a bomb or fireworks explode
  3. 3make something start to happen, or make someone start to laugh or cry
  1. 1

    Start a journey

    set off

    B1No object

    • We set off early to miss the traffic.
    • What time do you need to set off tomorrow?
    • They set off for the mountains after breakfast.
  2. 2

    Make an alarm ring or a bomb or fireworks explode

    set something off

    C2Separable

    • Burnt toast set off the smoke alarm again.
    • Kids were setting off fireworks in the park.
    • My belt set the alarm off at the airport.
  3. 3

    Make something start to happen, or make someone start to laugh or cry

    set somebody or something off

    C2Separable

    • His joke set everyone off laughing.
    • The news set off a wave of protests.
    • Don’t talk about her dog. It’ll set her off again.
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Is set off separable?

When set off means start a journey, it has no object. Add for the place you go: We set off for Rome. When it means make something go off, it is separable: set off the alarm, set the alarm off, set it off.

Set off and set out both mean start a journey. Set out also means start a task with a clear plan: She set out to write a book.

Verb tenses for set off

PresentI set off · she sets off
Pastset off
Present perfecthave set off
-ing formsetting off

Common mistakes with set off

What learners often say, and what to say instead.

  • Wrong: We set off to Rome at six in the morning.

    Right: We set off for Rome at six in the morning.

    Use for before the place you are travelling to.

  • Wrong: The smoke set off it.

    Right: The smoke set it off.

    A pronoun goes between set and off.

  • Wrong: Yesterday we setted off early.

    Right: Yesterday we set off early.

    Set does not change in the past: set off.

Synonyms and opposites of set off

Words close to it, and words that mean the opposite.

Similar

Opposite

  • arrivereach the end of a journey
  • turn backreturn before you reach where you were going

Set off quiz

Three quick questions. Pick an answer to see if it is right and why.

  1. 1It’s a long drive, so let’s ___ before sunrise.

  2. 2Choose the right sentence.

  3. 3“The cooking smoke set off the alarm.” What happened?

More phrasal verbs with set

5 phrasal verbs start with set. Test yourself on all of them in a few minutes.

Test yourself on setTake the full test

Set off FAQ

Questions people ask about set off.

Set off vs set out: what is the difference?

For journeys they mean the same. Set out sounds more planned or longer. Only set out means start a task: He set out to learn Greek.

Does set off mean turn off?

No. Set off an alarm means make it start ringing, the opposite of turning it off. To stop it, you turn it off.

What does set someone off mean?

It means make someone start laughing, crying or getting angry. One word from him can set her off.

Use set off in real conversations

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