c. 1400, "hardened," in the physical sense, from Latin callosus "thick-skinned," from callus, callum "hard skin" (see callus). The figurative sense of "unfeeling, hardened in the mind" appeared in English by 1670s. Related: Callously; callousness.
a callous indifference to suffering
calloused skin
with a workman's callous hands
calliper
callipygian
Callisto
callithumpian
callosal
callous
callow
callus
calm
calmative
calmly
