- when
- whenW1S1 [wen] adv, conj, pron[: Old English; Origin: hwanne, hwenne]1.) at what time▪ When are we leaving?▪ When did you first meet Dr Darnall?▪ When will the work be finished?▪ I don't know when I'll see her again.when to do sth▪ I'll tell you when to stop.2.) at or during the time that something happens▪ Leonard was nine when his father died.▪ When the family came here from Russia, they were penniless.▪ When he was in the airforce he flew Tornado jets.3.) after or as soon as something happens▪ When the meal was finished, Rachel washed up and made coffee.▪ I'll phone you again when I get home.4.) used to mention a type of event or situation when talking about what happens on occasions of that type▪ When lead is added to petrol, it improves the car's performance.▪ When mixed with water the powder forms a smooth paste.▪ He always wears glasses except when playing football.5.) used to show which particular time or occasion you are talking about▪ The best moment was when Barnes scored the winning goal.▪ There are times when I hate him.the day/time/afternoon etc when▪ She remembered the day when Paula had first walked into her office.6.) by/since whenbefore or since which time▪ The baby is due in May, by when the new house should be finished.▪ That was written in 1946, since when the education system has undergone great changes.7.) since when ...?spoken used to show that you are very surprised or angry▪ Since when have you been interested in my feelings?8.) even though something is true▪ Why does she steal things when she could easily afford to buy them?9.) used to introduce a fact or statement that makes something seem surprising▪ When you consider that the airline handled 80 million passengers last year, the accident figures are really very small.
Dictionary of contemporary English. 2013.