callous

a. [ L. callosus callous hard, fr. callum, callus, callous skin: cf. F. calleux. ] 1. Hardened; indurated. “A callous hand.” Goldsmith. “A callous ulcer.” Dunglison. [ 1913 Webster ]

2. Hardened in mind; insensible; unfeeling; unsusceptible. “The callous diplomatist.” Macaulay. [ 1913 Webster ]

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. [1913 Webster]

A callousness and numbness of soul. Bentley. [1913 Webster]

adj. having callouses; -- of skin.
Syn. -- thickened. [ WordNet 1.5 ]