'archaist' originates from Greek, specifically the word 'arkhaíos' (ἀρχαῖος), where the root meant 'ancient', and entered English via Latin/French forms with the suffix '-ist' added in modern English to denote an adherent.

'archaist' developed from Late Latin/French forms such as 'archaicus'/'archaïque' (meaning 'ancient' or 'old-fashioned'), which yielded English 'archaic', and the agentive suffix '-ist' was later attached to form 'archaist' (one who favors archaic forms).

Initially the Greek root meant 'ancient' or 'old'; over time the idea shifted into English to denote not just age but a preference for or advocacy of older forms, hence 'archaist' meaning 'one who favors archaic language or practices.'