(pron.) A relative pronoun, used esp. in referring to an antecedent noun or clause, but sometimes with reference to what is specified or implied in a sentence, or to a following noun or clause (generally involving a reference, however, to something which has preceded). It is used in all numbers and genders, and was formerly used of persons.
WHICH
Meaning of WHICH in English
Webster's English dictionary. Английский словарь Webster. 2012