when
Translation
at what time, at the time that
Examples
When is your birthday?
When is your birthday?
Call me when you arrive.
Call me when you arrive.
I was young when it happened.
I was young when it happened.
Grammar Patterns
when + [auxiliary verb] + [subject] ...? asks about time When does the train leave?
[clause] when [clause] indicates the time something happens I'll tell you when I know.
Similar Words
Synonyms: at what time, at the time that
Etymology
From Old English 'hwænne', meaning 'at what time'. Related to other 'wh-' words (what, where).
Memory Tips
Picture a clock face combined with a question mark. 'WHen' asks about 'WHat' time.