callous

Callous describes a hardened lack of feeling or sympathy toward others.

Someone callous is emotionally tough in a way that makes them indifferent to suffering: The callous remarks about the victims shocked everyone.

In its physical sense, callous refers to skin that has become thick and hardened, usually from repeated friction or pressure.

The verb callous means to make or become hardened in either sense.

The related noun is callus, the thickened skin itself.