The Collaborative International Dictionary of English v.0.48:

Sharp \Sharp\, v. t. [imp. & p. p. Sharped; p. pr. & vb. n.
   Sharping.]
   1. To sharpen. [Obs.] --Spenser.
      [1913 Webster]

   2. (Mus.) To raise above the proper pitch; to elevate the
      tone of; especially, to raise a half step, or semitone,
      above the natural tone.
      [1913 Webster]