when

whenconjunction

When most often says at what time something happens; less often it shows that something is a surprising or odd thing to do.

1. at the time thatat the time that something happens or happened

   A when clause names the time of the action in the main clause. It can come first, with a comma after it (When the phone rang, she was in the shower), or after the main clause, with no comma (She was in the shower when the phone rang). In a clause about the future, when normally takes the present tense, not will: I will call you when I arrive, not when I will arrive.

   • Call me when you get home.
   • When I was a child, we lived by the sea.
   • She was reading when the phone rang.
   • I'll tell you when I know more. (future time, present tense after when)

   Synonyms while; once

   Compare while (while points to a period of time during which something happens; when can point to a single point or a period); whenever (whenever means any time that, not one particular time); where; if; as

   1. aevery time that something happens

      When can describe a habit or a rule as well as a single event.

      • When it rains, this road floods.
      • The dog barks when someone knocks on the door.

   For translators (sense 1)

   Meaning across languages Some languages use one word for both when (a point in time) and if (a condition). English keeps them apart: when you arrive assumes it will happen; if you arrive does not.

   Grammar trap In a clause about future time, when is normally followed by the present tense, not will: when she arrives, not when she will arrive. Will can appear here only to show willingness or insistence.

2. although; considering thatalthough it seems strange or unnecessary that

   Used to show surprise or mild criticism: the main clause says or asks why the action in the when clause seems wrong or pointless. It often follows a question with why.

   • Why walk when you can drive?
   • She always takes the bus when she could easily walk.
   • He gave up when he was so close to finishing.

   Compare although (although is the more general word for a surprising contrast; when is used this way mainly after a question with why or a criticism)

   For translators (sense 2)

   Meaning across languages This contrastive use of when often needs a word meaning although or since in another language, not that language's usual word for time.

See also when (the question word when (When did you arrive?))