'patriotist' is formed from the noun 'patriot' plus the agent suffix '-ist' (from Greek/Latin-derived English suffix meaning 'one who practices or is concerned with').

'patriot' originates from Latin 'patria' meaning 'fatherland' via Greek 'patriōtēs' meaning 'fellow-countryman'; the English noun 'patriot' developed, and the suffix '-ist' was later attached to form 'patriotist' in occasional or archaic usage.

Originally connected to the idea of a 'fellow-countryman' or 'one of the same country,' the term evolved to mean someone who actively supports and defends their country; 'patriotist' carries the same core sense but is a less common/older formation.