Callous means hard-hearted and unfeeling. A callous remark, callous disregard, callously indifferent.
It is a serious criticism: callous means not merely failing to care but being unmoved by suffering that ought to move anybody. Callous disregard is the standard formula in judgments and inquiries. Note the spelling trap with callus, the patch of hardened skin, which is the same Latin word — the metaphor is of feeling worn hard, exactly as skin is. Note callously.
1adjectivecallousHard-hearted and unfeeling.
“It was callous of him to laugh when she told him her dog had died.”
callous is a quality of hardness.
Latin callosus means hard-skinned, from callum, hardened skin. A callus and a callous person are the same word: one skin hardened and one feeling.
Latin
callōsus — hard-skinned
English, today
callous
Built from
From Latin callōsus (“hard-skinned”), from callum (“hardened skin”) + -ōsus.
Etymology from Wiktionary, CC BY-SA