'bacchanalism' originates from Latin, specifically the word 'Bacchanalia', where 'Bacchan-' referred to the festivals of the god Bacchus (itself from Greek 'Bakkhos').

'bacchanalism' changed from the Latin word 'Bacchanalia' (used for the rites/festivals of Bacchus), passed through Late/Medieval Latin and Middle English forms, and eventually became the modern English word 'bacchanalism'.

Initially, it meant 'rites or festivals honoring Bacchus', but over time it evolved into its current meaning of 'riotous, drunken revelry or excessive indulgence'.