callus

noun

1. (countable, uncountable)A hardened area of the skin (especially on the foot or hand) caused by repeated friction, wear or use.

   “Sylvanshine had once been on a first date with a Xerox rep who had complex and slightly repulsive patterns of callus on her fingers from playing the banjo semi-professionally”

2. (countable, uncountable)The material of repair in fractures of bone; a substance exuded at the site of fracture, which is at first soft or cartilaginous in consistency, but is ultimately converted into true bone and unites the fragments into a single piece.
3. (countable, uncountable)The new formation over the end of a cutting, before it puts out rootlets.
4. (countable, uncountable)In orchids, a fleshy outgrowth from the labellum.
5. (countable, uncountable)In grasses, a hardened extension from the base of a floret, which may or may not elongate and is often covered in hairs or bristles.
6. (countable, uncountable)A shining area on the frons of many species of Tabanomorpha (horse flies and relatives).

verb

1. (intransitive)To form such hardened tissue.