adjective
callous
KAL-uhs/ˈkæləs/
Hardened and no longer sensitive.
His callous reply shows no concern for the injured worker.

Etymology
Originally describing physically hardened or thick skin, callous shifted to emotional hardness. Someone callous is figuratively hardened against other people's feelings or suffering.
In context
was the biggest overnight cut to welfare in 70 years. It would have been a callous act at any time
More examples
- Years of labor left her palms callous and rough.
- They condemned the callous treatment of the prisoners.
- Repeated exposure had made him callous toward suffering.
Forms
callous
callousness noun — Insensitivity to other people's suffering.
Similar words
- cruel
- May actively cause suffering, while callous emphasizes lack of sensitivity to it.