when
when / (h)wen/ • interrog. adv. at what time: when did you last see him? | since when have you been interested? ∎ how soon: when can I see you? ∎ in what circumstances: when would such a rule be justifiable?• relative adv. at or on which (referring to a time or circumstance): Saturday is the day when I get my hair done.• conj. 1. at or during the time that: I loved math when I was in school. ∎ after: call me when you're finished. ∎ at any time that; whenever: can you spare five minutes when it's convenient?2. after which; and just then (implying suddenness): he had just drifted off to sleep when the phone rang.3. in view of the fact that; considering that: why bother to paint it when you can photograph it with the same effect?4. although; whereas: I'm saying it now when I should have told you long ago.