'enthusiasm' originates from Greek, specifically the word 'enthousiasmos,' where 'en-' meant 'in' and 'theos' meant 'god.'

'enthousiasmos' transformed into the Latin word 'enthusiasmus,' and eventually became the modern English word 'enthusiasm' through Middle English.

Initially, it meant 'inspiration or possession by a god,' but over time it evolved into its current meaning of 'intense and eager enjoyment or interest.'