which / (h)wich/ • interrog. pron. & adj. asking for information specifying one or more people or things from a definite set: [as pron.] which are the best varieties of grapes for long keeping? which of the suspects murdered him? | [as adj.] which way is the wind blowing? • relative pron. & adj. used referring to something previously mentioned when introducing a clause giving further information: [as pron.] a conference in Vienna, which ended on Friday | [after prep.] it was a crisis for which he was totally unprepared | [as adj. , after prep.] your claim ought to succeed, in which case the damages will be substantial. PHRASES: 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.