Which

pronoun
1.
what one?:
Which of these do you want? Which do you want?
2.
whichever; any one that:
Choose which appeals to you.
3.
(used relatively in restrictive and nonrestrictive clauses to represent a specified antecedent):
The book, which I read last night, was exciting. The socialism which Owen preached was unpalatable to many. The lawyer represented five families, of which the Costello family was the largest.
4.
(used relatively in restrictive clauses having that as the antecedent):
Damaged goods constituted part of that which was sold at the auction.
5.
(used after a preposition to represent a specified antecedent):
the horse on which I rode.
6.
(used relatively to represent a specified or implied antecedent) the one that; a particular one that:
You may choose which you like.
7.
(used in parenthetic clauses) the thing or fact that:
He hung around for hours and, which was worse, kept me from doing my work.
8.
Nonstandard. who or whom:
a friend which helped me move; the lawyer which you hired.
adjective
9.
what one of (a certain number or group mentioned or implied)?:
Which book do you want?
10.
whichever; any that:
Go which way you please, you’ll end up here.
11.
being previously mentioned:
It stormed all day, during which time the ship broke up.
determiner
1.

used with a noun in requesting that its referent be further specified, identified, or distinguished from the other members of a class: which house did you want to buy?
(as pronoun): which did you find?
(used in indirect questions): I wondered which apples were cheaper

2.

whatever of a class; whichever: bring which car you want
(as pronoun): choose which of the cars suit you

3.
used in relative clauses with inanimate antecedents: the house, which is old, is in poor repair
4.
as; and that: used in relative clauses with verb phrases or sentences as their antecedents: he died of cancer, which is what I predicted
5.
(archaic) the which, a longer form of which, often used as a sentence connector
wherewithal, the