'feudalist' originates from Medieval Latin, specifically the word 'feodalis' (from 'feodum' or 'feudum'), where 'feodum/feudum' meant 'fief' or 'fee'. The English suffix '-ist' (from Greek/Latin via Old French) denotes 'one who practices or supports'.

'feudalist' developed from Medieval Latin 'feodalis', passed into Old French as 'feodal'/'féodal', then into Middle English as 'feudal', and finally formed as 'feudalist' in modern English by adding the agentive suffix '-ist'.

Initially it referred to matters or persons tied to the 'fief' system (land held by feudal tenure); over time it came to mean more broadly a supporter of feudal institutions or someone upholding feudal social relations.