'antifeudalist' originates from the prefix 'anti-' (from Greek 'antí' meaning 'against'), the adjective 'feudal' (from Medieval Latin 'feodalis', from 'feodum' meaning 'fief' or 'fee'), and the agentive suffix '-ist' (from Latin/French '-ista' meaning 'one who advocates or practices').

'antifeudalist' was formed in modern English by combining 'anti-' + 'feudal' + '-ist'. The element 'feudal' comes via Old French/Medieval Latin ('feodal', 'feodalis') from Latin 'feodum' (a fief), and the suffix '-ist' was added in English to denote an adherent or opponent.

Initially it meant 'a person opposed to feudalism' and over time it has largely retained that meaning, also used attributively as an adjective to describe opposition to feudal arrangements.