keratoma

noun

ker·​a·​to·​ma ˌker-ə-ˈtō-mə 

plural keratomas also keratomata -mət-ə 

1

: a hard thickened area of skin produced by hypertrophy of the horny layers : callus

2

: a tumorlike growth of horny tissue on the inner surface of the wall of a horse's hoof