na-adjective, noun
unkindness; heartlessness; inhumanity
Describes a lack of human warmth or compassion; often used for cold, unfeeling behavior.
彼の不人情な態度に皆が傷ついた。
Everyone was hurt by his heartless attitude.
そんな不人情なことは言えない。
I can't say such an unkind thing.
無情 means pitiless or merciless, often with a stronger nuance of cruelty; 不人情 is more about lacking ordinary human warmth.
Compound of 不 (negative prefix) and 人情 (humanity, kindness). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of lacking human warmth.