'archheretic' originates from Greek, specifically the prefix 'arch-' from 'arkhos' where 'arkhos' meant 'chief', combined with Greek 'hairetikos' (via Latin 'haereticus'), where 'hairetikos' meant 'able to choose' or 'sectarian'.

'archheretic' developed by combining the Greek-derived prefix 'arch-' (chief) with the word that came into English from Latin 'haereticus' (from Greek 'hairetikos') through Old French and Middle English ('heretike' / 'heretique'), eventually forming the compound (often hyphenated) 'arch-heretic' in Early Modern English.

Initially it carried the literal sense of 'chief or foremost heretic', and over time it has remained an emphatic label for an extreme or notorious heretic rather than indicating a formal rank.