inhumane comes from in- ('not') + humane, the latter a variant of human specialized to mean 'compassionate', ultimately from Latin humanus, from homo ('man, human being'). Morphologically, the prefixed shape matters: the initial element belongs to the recorded formation and helps explain the modern form's surface analysis. In present English, the adjective sense is "lacking compassion or kindness; cruel", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as humane, inhuman, and humanity, and in derivatives such as inhumanely. Its semantic neighborhood includes cruel, heartless, merciless, and brutal, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin in-, Latin humanus, and Latin homo.