'antinationalistic' originates from Modern English, formed by the prefix 'anti-' (from Greek 'anti' meaning 'against') combined with 'nationalistic' (from 'nationalism' + the adjectival suffix '-istic').

'nationalistic' developed from 'nationalism' (from French 'nationalisme' and Latin 'natio' meaning 'birth, nation'); the combining prefix 'anti-' comes from Greek 'anti' meaning 'against'. The full compound 'antinationalistic' was created in Modern English by joining these elements.

Initially the elements separately signified 'against' + 'nation/nationalism'; over time the compound has come to be used specifically to describe attitudes or positions opposed to nationalism or nationalistic policies.