Source : Webster's Revised Unabridged Dictionary (1913)

Callosity \Cal*los"i*ty\, n.; pl. {Callosities}. [L. callasitas;
   cf. F. calost['e].]
   A hard or thickened spot or protuberance; a hardening and
   thickening of the skin or bark of a part, eps. as a result of
   continued pressure or friction.

Source : WordNet®

callosity
     n : an area of skin that is thick or hard from continual
         pressure or friction (as the sole of the foot) [syn: {callus}]