'antihuman' originates from modern English, specifically the prefix 'anti-' and the word 'human', where 'anti-' meant 'against' and 'human' meant 'human being'.

'anti-' comes from Greek 'antí' meaning 'against', and 'human' comes via Latin 'humanus' (and Old French 'humain') meaning 'human'; compounds with 'anti-' + substantive forms have been formed in English since the 19th–20th centuries, producing terms like 'antihuman'.

Initially formed to mean 'against humans' or 'opposed to humanity'; this core meaning has largely remained, though it is also used more specifically to describe dehumanizing attitudes or policies.