say it: KAL-uhs
callous is an adjective and verb meaning "emotionally hardened". It carries 3 recorded senses.
emotionally hardened
“a callous indifference to suffering”
“cold-blooded and indurate to public opinion”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for callous come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.