'anti-medievalism' originates from Modern English, specifically from the combining prefix 'anti-' (from Greek 'anti-' meaning 'against'), the adjective 'medieval' (from Medieval Latin 'medium aevum' meaning 'middle age' via Old French/Latin), and the suffix '-ism' (from Greek '-ismos' via Latin/French indicating doctrine or movement).

'anti-' comes from Greek 'anti-' and entered English via Late Latin and French; 'medieval' was formed in Modern English from Medieval Latin 'medium aevum' ('medium' + 'aevum') through Old French and scholarly Latin; the suffix '-ism' derives from Greek '-ismos' via Latin and French, and English combined these elements into 'anti-medievalism' to name the stance or doctrine opposed to medievalism.

Initially the components signified 'against the middle ages' or 'against medieval practices'; over time the compound has been used specifically to mean opposition to 'medievalism' (the revival/romanticization of medieval culture) and also more broadly to negative attitudes toward the historical Middle Ages.