cal·lus   (kāl'əs)    n.   pl. cal·lus·es A localized thickening and enlargement of the horny layer of the skin. Also called callosity. The hard bony tissue that develops around the ends of a fractured bone during healing. Undifferentiated tissue that develops on or around an injured or cut plant surface or in tissue culture. The hardened, sometimes sharp base of the floret of certain grasses. Botany Undifferentiated tissue that develops on or around an injured or cut plant surface or in tissue culture. The hardened, sometimes sharp base of the floret of certain grasses. intr.v.   cal·lused, cal·lus·ing, cal·lus·es To form or develop such hardened tissue. See Usage Note at callous. [Latin, masculine of callum.]

Callus

Cal"lus\, n. [L. See Callous.]

1. (Med.) (a) Same as Callosity. (b The material of repair in fractures of bone; a substance exuded at the site of fracture, which is at first soft or cartilaginous in consistence, but is ultimately converted into true bone and unites the fragments into a single piece.

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

callus  (n.)

Main Entry: cal·lus
Pronunciation: 'kal-&s
Function: noun
1 : a thickening of or a hard thickened area on skin
2 : amass of exudate and connective tissue that forms around a break in a bone and is converted into bone in the healing of the break

callus cal·lus (kāl'əs)
n. pl. cal·lus·es

1. See callosity.
2. The hard bony tissue that develops around the ends of a fractured bone during healing.

callus   (kāl'əs)  Pronunciation Key  An area of the skin that has become hardened and thick, usually because of prolonged pressure or rubbing. The hard bony tissue that develops around the ends of a fractured bone during healing.