Definition of "callus" in English

noun

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

2. 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. (botany) The new formation over the end of a cutting, before it puts out rootlets.

4. (botany) In orchids, a fleshy outgrowth from the labellum.

5. (botany) 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. (entomology) A shining area on the frons of many species of Tabanomorpha (horse flies and relatives).

verb

1. (intransitive) To form such hardened tissue.