'anti-mysticism' is a modern English compound formed from the prefix 'anti-' (from Greek 'anti', meaning 'against') plus 'mysticism' (from Greek 'mystikos'/'mysterion' via Latin/French).

'mysticism' comes from Greek 'mysterion' (secret rite, mystery) → Late Latin 'mysticus' → Old French/Medieval Latin forms → Middle English 'mysticism'; the prefix 'anti-' (Greek 'anti-') was later attached in modern English to create 'anti-mysticism'.

Originally 'mysticism' referred to secret rites or mysteries; over time it came to mean doctrines and practices claiming direct, immediate experience of the divine or ultimate reality. 'Anti-mysticism' therefore developed to denote opposition to those doctrines and practices.