'archfiend' originates from English, formed by the prefix 'arch-' + 'fiend', where 'arch-' comes from Greek 'arkhi-' meaning 'chief' and 'fiend' traces to Old English 'fēond' meaning 'enemy'.

'arch-' (from Greek 'arkhi-' via Latin/Old French) combined with Old English 'fēond' (Middle English 'feond'/'fiend') to form Middle English/early Modern English compounds such as 'archfiend', which became the modern English 'archfiend'.

Initially it referred specifically to a chief demon or principal evil spirit; over time it also acquired a figurative sense of a chief human enemy or arch‑villain.