—n. 1. Pathol.,Physiol. a. a hardened or thickened part of the skin; a callosity.
b. a new growth of osseous matter at the ends of a fractured bone, serving to unite them.
2. Also,callose.Bot. a. the tissue that forms over the wounds of plants, protecting the inner tissues and causing healing.
b. a deposit on the perforated area of a sieve tube.
c. (in grasses) a tough swelling at the base of a lemma or palea.
—v.i. to form a callus.
—v.t. to produce a callus or calluses on: Heavy work callused his hands.