'archmystagogue' originates from Greek elements: the prefix 'archi-' (from ἀρχι-, meaning 'chief, principal') combined with 'mustagōgos' (μυσταγωγός, meaning 'one who leads the initiated' or 'initiator into mysteries'), where 'archi-' meant 'chief' and 'mustagōgos' meant 'leader/guide into mysteries'.

'mystagogue' derives from Greek 'mustagōgos', passed into Late Latin as 'mystagogus' and into English as 'mystagogue'; English later formed the compound by prefixing 'arch-' to produce 'archmystagogue', literally 'chief mystagogue'.

Initially it denoted 'the chief leader who initiates others into secret or religious rites'; the sense has largely remained, though the term is now rare and is sometimes used figuratively for a leading teacher or guide into specialized or esoteric knowledge.