The Collaborative International Dictionary of English v.0.48:

Corn \Corn\ (k[^o]rn), n. [L. cornu horn: cf. F. corne horn,
   hornlike excrescence. See Horn.]
   A thickening of the epidermis at some point, esp. on the
   toes, by friction or pressure. It is usually painful and
   troublesome.
   [1913 Webster]

         Welcome, gentlemen! Ladies that have their toes
         Unplagued with corns, will have a bout with you.
                                                  --Shak.
   [1913 Webster]

   Note: The substance of a corn usually resembles horn, but
         where moisture is present, as between the toes, it is
         white and sodden, and is called a soft corn.
         [1913 Webster]

WordNet (r) 3.0 (2006):

soft corn
    n 1: corn having kernels almost entirely of soft starch [syn:
         soft corn, flour corn, squaw corn, Zea mays
         amylacea]