'aion' originates from Ancient Greek, specifically the word 'αἰών', where 'αἰών' meant 'eternity' or 'age'.

'αἰών' transformed into the Latin word 'aevum', and eventually became the modern English word 'eon' through Old French.

Initially, it meant 'eternity' or 'age', and this meaning has largely remained the same in modern usage.