callous / callus are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
callous: (verb) make insensitive or callous; deaden feelings or morals. (adjective) emotionally hardened.
callus: (noun) bony tissue formed during the healing of a fractured bone. (noun) (botany) an isolated thickening of tissue, especially a stiff protuberance on the lip of an orchid. (verb) cause a callus to form on. (verb) form a callus or calluses.
callous: k·AE·l·ah·s
callus: k·AE·l·ah·s
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)