'anti' originates from Greek, specifically the word 'antí', where 'anti-' meant 'against'.

'anti' entered English via Latin and Old French as the combining form 'anti-' in Medieval Latin and Middle English and eventually became the modern English element and standalone word 'anti'.

Initially it meant 'against' in a general sense; over time it retained that core sense while also developing use as a prefix and as a standalone noun meaning 'an opponent' or 'those opposed'.