Nouns

(n)callosity, callusan area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)
(n)callusbony tissue formed during the healing of a fractured bone
(n)callus(botany) an isolated thickening of tissue, especially a stiff protuberance on the lip of an orchid

Verbs

(v)calluscause a callus to form on“The long march had callused his feet”
(v)callusform a callus or calluses“His foot callused”