[1] : The Collaborative International Dictionary of English v.0.48

what \what\ hwo^t, pron., a.,  adv. as. hwaet, neuter of
   hw=a who; akin to os. hwat what, ofries. hwet, d.  lg.
   wat, g. was, ohg. waz, hwaz, icel. hvat, sw.  dan. hvad,
   goth. hwa. root182. see who.
   1913 webster
   1. as an interrogative pronoun, used in asking questions
      regarding either persons or things; as, what is this? what
      did you say? what poem is this? what child is lost?
      1913 webster

            what see'st thou in the ground?       --shak.
      1913 webster

            what is man, that thou art mindful of him? --ps.
                                                  viii. 4.
      1913 webster

            what manner of man is this, that even the winds and
            the sea obey him                     --matt. viii.
                                                  27.
      1913 webster

   note: originally, what, when, where, which, who, why, etc.,
         were interrogatives only, and it is often difficult to
         determine whether they are used as interrogatives or
         relatives.
         1913 webster what in this sense, when it refers to
         things, may be used either substantively or
         adjectively; when it refers to persons, it is used only
         adjectively with a noun expressed, who being the
         pronoun used substantively.
         1913 webster

   2. as an exclamatory word:
      a used absolutely or independently; -- often with a
          question following. "what welcome be thou." --chaucer.
          1913 webster

                what, could ye not watch with me one hour?
                                                  --matt. xxvi.
                                                  40.
          1913 webster
      b used adjectively, meaning how remarkable, or how
          great; as, what folly what eloquence what courage
          1913 webster

                what a piece of work is man      --shak.
          1913 webster

                o what a riddle of absurdity     --young.
          1913 webster

   note: what in this use has a or an between itself and its
         noun if the qualitative or quantitative importance of
         the object is emphasized.
         1913 webster
      c sometimes prefixed to adjectives in an adverbial
          sense, as nearly equivalent to how; as, what happy
          boys
          1913 webster

                what partial judges are our love and hate
                                                  --dryden.
          1913 webster

   3. as a relative pronoun: 
      1913 webster
      a used substantively with the antecedent suppressed,
          equivalent to that which, or those persons who, or
          those things which; -- called a compound relative.
          1913 webster

                with joy beyond what victory bestows. --cowper.
          1913 webster

                i'm thinking captain lawton will count the noses
                of what are left before they see their
                whaleboats.                       --cooper.
          1913 webster

                what followed was in perfect harmony with this
                beginning.                        --macaulay.
          1913 webster

                i know well . . . how little you will be
                disposed to criticise what comes to you from me.
                                                  --j. h.
                                                  newman.
          1913 webster
      b used adjectively, equivalent to the . . . which; the
          sort or kind of . . . which; rarely, the . . . on, or
          at, which.
          1913 webster

                see what natures accompany what colors. --bacon.
          1913 webster

                to restrain what power either the devil or any
                earthly enemy hath to work us woe. --milton.
          1913 webster

                we know what master laid thy keel,
                what workmen wrought thy ribs of steel.
                                                  --longfellow.
          1913 webster
      c used adverbially in a sense corresponding to the
          adjectival use; as, he picked what good fruit he saw.
          1913 webster

   4. whatever; whatsoever; what thing soever; -- used
      indefinitely. "what after so befall." --chaucer.
      1913 webster

            whether it were the shortness of his foresight, the
            strength of his will, . . . or what it was. --bacon.
      1913 webster

   5. used adverbially, in part; partly; somewhat; -- with a
      following preposition, especially, with, and commonly with
      repetition.
      1913 webster

            what for lust pleasure and what for lore.
                                                  --chaucer.
      1913 webster

            thus, what with the war, what with the sweat, what
            with the gallows, and what with poverty, i am custom
            shrunk.                               --shak.
      1913 webster

            the year before he had so used the matter that what
            by force, what by policy, he had taken from the
            christians above thirty small castles. --knolles.
      1913 webster

   note: in such phrases as i tell you what, what anticipates
         the following statement, being elliptical for what i
         think, what it is, how it is, etc. "i tell thee what,
         corporal bardolph, i could tear her." --shak. here what
         relates to the last clause, "i could tear her;" this is
         what i tell you.
         what not is often used at the close of an enumeration
         of several particulars or articles, it being an
         abbreviated clause, the verb of which, being either the
         same as that of the principal clause or a general word,
         as be, say, mention, enumerate, etc., is omitted. "men
         hunt, hawk, and what not." --becon. "some dead puppy,
         or log, or what not." --c. kingsley. "battles,
         tournaments, hunts, and what not." --de quincey. hence,
         the words are often used in a general sense with the
         force of a substantive, equivalent to anything you
         please, a miscellany, a variety, etc. from this arises
         the name whatnot, applied to an 'etag`ere, as being
         a piece of furniture intended for receiving
         miscellaneous articles of use or ornament.
         1913 webster but what is used for but that, usually
         after a negative, and excludes everything contrary to
         the assertion in the following sentence. "her needle is
         not so absolutely perfect in tent and cross stitch but
         what my superintendence is advisable." --sir w. scott.
         "never fear but what our kite shall fly as high." --ld.
         lytton.
         1913 webster

   what ho an exclamation of calling.

   what if, what will it matter if; what will happen or be the
      result if. "what if it be a poison?" --shak.

   what of this? what of that? what of it? etc., what
      follows from this, that, it, etc., often with the
      implication that it is of no consequence; so what? "all
      this is so; but what of this, my lord?" --shak. "the night
      is spent, why, what of that?" --shak.

   what though, even granting that; allowing that; supposing
      it true that. "what though the rose have prickles, yet't
      is plucked." --shak.

   what time, or what time as, when. obs. or archaic "what
      time i am afraid, i will trust in thee." --ps. lvi. 3.
      1913 webster

            what time the morn mysterious visions brings.
                                                  --pope.
      1913 webster
see also:
who what ho what if what of this? what of that? what of it? 
what though what time what time as 

What >> W Words
What, definition of term: What
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Though >> T Words
Though, definition of term: Though
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What If >> W Words
What If, definition of term: What If
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Even Though >> E Words
Even Though, definition of term: Even Though
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Abstract Though >> A Words
Abstract Though, definition of term: Abstract Though
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What Is Up >> W Words
What Is Up, definition of term: What Is Up
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