WordNet sense 1 (having calluses; having skin made tough and thick through wear):

calloused, thickened

WordNet sense 2 (physically toughened):

tough, toughened

WordNet sense 3 (emotionally hardened):

indurate, pachydermatous

WordNet sense 4 (deficient in human sensibility; not mentally or morally sensitive):

insensitive

WordNet sense 5 (make insensitive or callous; deaden feelings or morals):

cauterize, cauterise