'diadem' originates from Greek, specifically the word 'διάδημα' (diádēma), where 'dia-' meant 'through' and 'dēma' meant 'to bind.'

'διάδημα' transformed into the Latin word 'diadema,' and eventually became the modern English word 'diadem' through Old French.

Initially, it meant 'a band or fillet,' but over time it evolved into its current meaning of 'a crown or headband worn as a symbol of sovereignty.'