Webster's Revised Unabridged Dictionary · 1913

Callous

Callous , adjective

[Latin callosus callous hard, from callum, callus, callous skin: compare French calleux.]

1.
Hardened; indurated.
A callous hand. — Goldsmith
A callous ulcer. — Dunglison
2.
Hardened in mind; insensible; unfeeling; unsusceptible.
The callous diplomatist. — Macaulay
It is an immense blessing to be perfectly callous to ridicule. — T. Arnold
A callousness and numbness of soul. — Bentley