which

from The Century Dictionary.

• noun A chest.
• noun Specifically, a movable wagon-box.
• A. interrog. What one of a certain implied number or set? indicating a general knowledge of a certain group of individuals, and seeking for a selection of one or more from that number: thus, which do you want? implying a limitation which is absent from the question what do you want?
• B. rel. As a simple relative pronoun: Who or whom.
• Used with, reference to things, and to creatures not persons: the antecedent may also be a phrase or a clause: as, the rain washed away the track, which delayed the train.
• As a compound relative pronoun, having the value of both antecedent and relative: as, you can determine which is better (that is, you can determine that, or the one, which is better).
• Which is used adjectively:
• With the sense of ‘what sort of.’
• As indicating one of a number of known or specified things: as, be careful which way you turn.
• [Which was formerly used as a clause-connective, along with a personal pronoun which took its place as subject or object, and rendered it redundant save as in its relative value: as, which … he = who; which … his = whose.
• A relic of this construction survives in the vulgar use of which as a general introductory word.
• Which was formerly often followed by that or as, having the effect of giving emphasis or definiteness.
• Redundant for which.

from the GNU version of the Collaborative International Dictionary of English.

• pronoun obsolete Of what sort or kind; what; what a; who.
• pronoun A interrogative pronoun, used both substantively and adjectively, and in direct and indirect questions, to ask for, or refer to, an individual person or thing among several of a class; See the Note under What, pron., 1.
• pronoun 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.
• pronoun A compound relative or indefinite pronoun, standing for any one which, whichever, that which, those which, the … which, and the like.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• determiner What, of those mentioned or implied (used interrogatively).
• determiner interrogative What one or ones (of those mentioned or implied).
• determiner relative The one or ones that.
• determiner relative the one mentioned
• determiner now dialectal Used of people (now generally who, whom or that).
• pronoun relative Who; whom; what (of those mentioned or implied)
• noun An occurrence of the word which.