Source : Webster's Revised Unabridged Dictionary (1913)

Which \Which\, pron. [OE. which, whilk, AS. hwilc, hwylc, hwelc,
   from the root of hw[=a] who + l[=i]c body; hence properly, of
   what sort or kind; akin to OS. hwilik which, OFries. hwelik,
   D. welk, G. welch, OHG. wel[=i]h, hwel[=i]h, Icel.
   hv[=i]l[=i]kr, Dan. & Sw. hvilken, Goth. hwileiks, hw?leiks;
   cf. L. qualis. ????. See {Who}, and {Like}, a., and cf.
   {Such}.]
   1. Of what sort or kind; what; what a; who. [Obs.]

            And which they weren and of what degree. --Chaucer.

   2. 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; as, which man is it? which woman was
      it? which is the house? he asked which route he should
      take; which is best, to live or to die? See the Note under
      {What}, pron., 1.

            Which of you convinceth me of sin?    --John viii.
                                                  46.

   3. 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.

            And when thou fail'st -- as God forbid the hour! --
            Must Edward fall, which peril heaven forfend!
                                                  --Shak.

            God . . . rested on the seventh day from all his
            work which he had made.               --Gen. ii. 2.

            Our Father, which art in heaven.      --Matt. vi. 9.

            The temple of God is holy, which temple ye are. --1
                                                  Cor. iii. 17.

   4. A compound relative or indefinite pronoun, standing for
      any one which, whichever, that which, those which, the . .
      . which, and the like; as, take which you will.

   Note: The which was formerly often used for which. The
         expressions which that, which as, were also sometimes
         used by way of emphasis.

               Do not they blaspheme that worthy name by the
               which ye are called?               --James ii. 7.

   Note: Which, referring to a series of preceding sentences, or
         members of a sentence, may have all joined to it
         adjectively. ``All which, as a method of a
         proclamation, is very convenient.'' --Carlyle.