Source : Webster's Revised Unabridged Dictionary (1913)

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.

   {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}? {that?} {it?} etc., what follows from this,
      that, it, etc., often with the implication that it is of
      no consequence. ``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.

            What time the morn mysterious visions brings.
                                                  --Pope.