or CALLOSITY, in a general sense, any cutaneous, cornaceous, or osseous hardness, whether natural or preternatural; but most frequently it means the callus generated about the edges of a fracture, provided by nature to preserve the fractured bones, or divided parts, in the situation in which they are replaced by the surgeon. A callus, in this last sense, is a sort of jelly, or liquid viscous matter, that sweats out from the finest arteries and bony fibres of the divided parts, and fills up the chinks or cavities between them. It first appears of a cartilaginous substance; but at length becomes quite bony, and joins the fractured part so firmly together, that the limb will often make greater resistance to any external violence, with this part than with those which were never broken.

CALLUS is also a hard, dense, insensible knob, rising on the hands, feet, &c., by much friction and pressure against hard bodies.