# when

/ˈhwɛn/ (US) · /wˈɛn/ (UK) · CEFR A1 · Conjunction

Source: https://englishreference.com/word/when
Updated: 2026-05-02

## Definition

at the time that something happens. You use this to connect two events or to ask about a specific time.

For teachers: at or during the time that something occurs. Functions as a subordinating conjunction to introduce temporal clauses or as a relative adverb in certain syntactic structures.

## Examples

- I will call you when I arrive at the station.
- The lights usually flicker when the old elevator starts moving in the hallway.
- When the final results were eventually published, the research team discovered that their initial hypothesis had been correct all along.

## Pitfalls

- Not "I will tell him when he will arrive." but "I will tell him when he arrives." — In future-time clauses introduced by 'when', use the present simple tense instead of 'will'.

## Usage notes

- Commonly used to introduce a subordinate clause; when the 'when' clause comes first, it is usually followed by a comma.

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