Webster’s Revised Unabridged Dictionary · 1913
Callous
Cal′lous (kăl′lŭs), a. [L. callosus callous hard, fr. callum, callus, callous skin: cf. F. 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.
Syn. — Obdurate; hard; hardened; indurated; insensible; unfeeling; unsusceptible. See Obdurate.
— Cal′lous·ly, adv. — Cal′lous·ness, n.
A callousness and numbness of soul. Bentley.