Source : Webster's Revised Unabridged Dictionary (1913)

Clavus \Cla"vus\, n. [L., a nail.]
   A callous growth, esp. one the foot; a corn.

Source : WordNet®

clavus
     n : a hard thickening of the skin (especially on the top or
         sides of the toes) caused by the pressure of ill-fitting
         shoes [syn: {corn}]