From Wiktionary
which is one of the 1000 most common headwords.
whether - which - while



in accents with the wine-whine merger



  1. (question) You use which to ask for the selection of one or more members of some set.
    There are a lot of new books this year. Which ones do you like?
    Excuse me, which way is the toilet?
    Which of the two wines is cheaper?
    Which of the following cheeses are usually made from sheep's milk? A. pecorino B. vaccino C. provolone D. chevre.
  2. (definite) (relative) You use which to add a clause to explain what thing you're talking about.
    For several seconds he sat in silence, during which time the tea and sandwiches arrived.
    I'm thinking of getting a new car, in which case I'd get a red one.



  1. (relative) You use which to add a clause to give more information about the thing you're talking about.
    We've met some problems which are very difficult to handle.
    He walked by a door with a sign which reads: PRIVATE OFFICE.
    He had to leave, which was very difficult.
    We have to protect the environment in which we live.
    She appears to actually like the man, which I find incredible.
    No art can be properly understood apart from the culture of which it is a part.