Inhuman means lacking human qualities altogether — cold, alien, not recognisably human. Inhumane means cruel: failing to show the compassion expected of people. Inhuman conditions sound otherworldly; inhumane conditions are the phrase you want for cruelty.
The core difference
One denies humanity as a category; the other denies kindness.
- inhuman — without human qualities: an inhuman screech, inhuman endurance.
- inhumane — cruel, lacking compassion: inhumane treatment.
The overlap
Inhuman is also used of extreme cruelty — "inhuman treatment" appears in serious legal instruments including human-rights conventions, where it means cruelty so severe it seems beyond human. So the overlap is real and long-established rather than an error.
Choosing
For cruelty in ordinary writing, inhumane is the precise word. Reserve inhuman for things that genuinely seem not human — a sound, a capacity, a degree of endurance.
Frequently asked questions
Which word means cruel?
Inhumane. Inhuman means lacking human qualities, though it is also used for cruelty so extreme it seems beyond human.
Is "inhuman treatment" wrong?
No. It appears in human-rights instruments with an established meaning of severe cruelty.
What is the noun form?
Inhumanity covers both senses. There is no common noun formed from inhumane.