callosity

1. The condition of being calloused.
2. Hardheartedness; insensitivity.
3. See callus (sense ).

[Middle English callosite, from Old French, from Late Latin callōsitās, from Latin callōsus, callous. See callous.]

A thickening and hardening of the outer horny layer of skin. A callus protects the skin from rubbing, but it can crack and become painful (see spinner's finger). The tightening of the skin that accompanies callus formation may also cause pain. In the early stages, calluses can be gently filed down with a pumice stone. A thick callus that causes pain should be dealt with by a doctor who might pare off the excess skin with a blade or use some other technique (e.g. a salicylic acid plaster) for removing the hardened skin.

A localized thickening and enlargement of the horny layer of the skin. Also called callus, keratoma, poroma, tyloma.

A callus.

The noun has one meaning:

Meaning #1: an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)
  Synonym: callus