callus

(noun) an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot). Synonyms: callosity.

(noun) bony tissue formed during the healing of a fractured bone.

(noun) (botany) an isolated thickening of tissue, especially a stiff protuberance on the lip of an orchid.

(verb) cause a callus to form on. Example: "The long march had callused his feet."

(verb) form a callus or calluses. Example: "His foot callused."