Definition of which in English:


interrogative pronoun & determiner

  • Asking for information specifying one or more people or things from a definite set.

    as pronoun ‘which are the best varieties of grapes for long keeping?’
    ‘which of the suspects murdered him?’
    as determiner ‘which way is the wind blowing?’
    • ‘What do you feel about this friend and which of his or her qualities do you see in yourself?’
    which, a fact which, something which
    View synonyms

relative pronoun & determiner

  • Used referring to something previously mentioned when introducing a clause giving further information.

    as pronoun ‘a conference in Vienna which ended on Friday’
    after preposition ‘it was a crisis for which he was totally unprepared’
    as determiner , after preposition ‘your claim ought to succeed, in which case the damages will be substantial’
    • ‘You really must have your own work area which can be cut off from the rest of the house.’
    • ‘He spent the night in the house of the evil spirit which was no longer able to live there.’
    • ‘As we took the top out of it I found a huge nest which is what I assume was the magpie house.’
    • ‘So we do not need to step out of the house for days, which I am so looking forward to.’
    • ‘It is often used to refer to a sort of social meeting in which it is pleasant to be together.’
    • ‘The game can also end if the stock runs out of cards, in which case the result is a draw.’
    • ‘This is not to mention the trauma of fear and terror of the bombing which has no end.’
    • ‘It was of average size for a house of the particular period in which it had been built.’
    • ‘They return to spawn in the same stream in which they were born, and die a few days later.’
    • ‘Cars go out in the first session in the order in which they finished the previous race.’
    • ‘There he had a nest over the window of a house in which dwelt the writer of fairy tales.’


In US English, it is usually recommended that which be employed only for nonrestrictive (or nonessential) clauses: the horse, which is in the paddock, is six years old (the which clause contains a nonessential fact, noted in passing; the horse would be six years old wherever it was). A that clause is restrictive (or essential), as it identifies a particular thing: the horse that is in the paddock is six years old (not any horse, but the one in the paddock). See also restrictive and that


  • which is which

    • Used when two or more people or things are difficult to distinguish from each other.

      ‘there is no confusion as to which is which’
      • ‘I can't recall offhand which is which (though you could figure it out.’
      • ‘I'll let you figure out which is which, it's not much of a puzzler.’
      • ‘And that can make it hard to distinguish which is which.’
      • ‘I can, like the animals on the farm, no longer tell which is which.’
      • ‘One is for a gift and one is for a service, but I can never remember which is which.’
      • ‘I'm just having trouble figuring out which is which!’
      • ‘The writers suggest ways to distinguish which is which in any given congregation.’
      • ‘I keep getting them mixed up, and I have to concentrate to remember which is which, and it's annoying.’
      • ‘The interrogator talks to both via a teletype machine, and his goal is to figure out which is which.’
      • ‘By the time you're done mixing it all together, it's hard to tell which is which.’


Old English hwilc, from the Germanic bases of who and alike.