'archfelon' originates from English, specifically from the elements 'arch-' (via Latin/Old French ultimately from Greek 'arkh-'/ 'arkhos') and Old French 'felon', where 'arch-' meant 'chief' or 'principal' and 'felon' meant 'wicked person' or 'criminal'.

'archfelon' changed from Middle English use combining 'arch-' + Old French 'felon' (Middle English forms attested in legal and literary texts) and remained in Early Modern English before becoming rare/archaic in contemporary usage.

Initially it meant 'the principal or chief felon' in legal or descriptive contexts; over time it came to be used more generally for a notorious or especially wicked criminal and is now considered archaic or literary.