callus-, callous- +

(Latin: hardened skin, thick skin; a knob)

A circumscribed thickening and hypertrophy of the horny layer of the skin.
1. A localized thickening and enlargement of the horny layer of the skin.
2. The osseous material woven between the ends of a fractured bone that is ultimately replaced by true bone in the healing process.
callous (adjective); more callous, most callous
Descriptive of a person who is emotionally hardened, unfeeling, and who is indifferent to the sufferings of other people: When Margery read the poetry that she had created to her English class, some of the students laughed in a very callous or insensitive manner.
A reference to an unfeeling attitude and without sympathy.
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Pertaining to having no consideration for another person.
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Relating to performing an unacceptable and heartless action.
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Having skin made tough and thick through wear; such as, her calloused skin was a result of her kind of work.
1. Having calluses; toughened: "He had callousness on the skin of his elbow."
2. This calloiusness has nothing to do with the descriptive term meaning, "emotionally hardened; unfeeling" and the two usages should not be used for the same application.
1. A localized firm thickening of the upper layer of skin as a result of repetitive friction or pressure.

A callus on the skin of the foot has become thick and hard from rubbing (as a result of repetitive friction). Calluses of the feet may lead to other problems such as serious infections. Shoes that fit well can keep calluses from forming on the feet.

2. The hard new bone substance, or mass of fibrous tissue, calcium, cartilage, and bone that forms progressively during the healing of a bone fracture.

Bony callus is part of the bone repair process.

3. Plant tissue that forms at the site of a wound, or that develops during tissue culture of plant parts, giving rise to new plantlets.
definitive callus
The exudate, found between two ends of a fractured bone, that develops into true bone.
provisional callus
A temporary deposit between the ends of a fractured bone that is reabsorbed when the true bone develops.

Cross references directly, or indirectly, involving the "skin": chorio-; cicatri- (scar); cori-; cuti-; hymen-; lepido- (scab, scale); papulo- (pimple); psoro- (itch, mange); pustu- (blister, pimple); rhytid- (wrinkle); scabio- (mange, itchy); sebo- (grease, oil).