'antimedieval' originates from English, specifically formed by combining the prefix 'anti-' (from Greek 'anti', meaning 'against') with 'medieval' (from Medieval Latin 'medium aevum', meaning 'middle age').

'medieval' comes from Medieval Latin 'medium aevum' -> Old French/Latin influence -> Middle English 'medieval'; the prefix 'anti-' comes from Greek 'anti' and has long been used in English to form adjectives meaning 'against'. Together they produced the modern compound 'antimedieval'.

Initially the elements signified 'against the middle age(s)', and over time the compound has been used to describe opposition to medieval ideas, institutions, aesthetics, or movements ('opposed to medievalism').