sharpen \sharp"en\, v. t. imp.  p. p. sarpened; p. pr.  vb.
   n. sharpening. see sharp, a.
   to make sharp. specifically:
   a to give a keen edge or fine point to; to make sharper;
       as, to sharpen an ax, or the teeth of a saw.
   b to render more quick or acute in perception; to make more
       ready or ingenious.
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             the air . . . sharpened his visual ray
             to objects distant far.              --milton.
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             he that wrestles with us strengthens our nerves and
             sharpens our skill.                  --burke.
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   c to make more eager; as, to sharpen men's desires.
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             epicurean cooks
             sharpen with cloyless sauce his appetite. --shak.
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   d to make more pungent and intense; as, to sharpen a pain
       or disease.
   e to make biting, sarcastic, or severe. "sharpen each
       word." --e. smith.
   f to render more shrill or piercing.
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             inclosures not only preserve sound, but increase
             and sharpen it.                      --bacon.
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   g to make more tart or acid; to make sour; as, the rays of
       the sun sharpen vinegar.
   h mus. to raise, as a sound, by means of a sharp; to
       apply a sharp to.
       1913 webster
see also:
sarpened sharpening sharp