diadem
🇺🇸
/ˈdaɪədem/
🇬🇧
/ˈdaɪədem/
A fancy crown or headband with jewels that a king or queen wears.
The queen wore a glittering diadem at her coronation ceremony.
A simple headband that shows someone has power or a high position.
The ancient ruler was depicted wearing a diadem, showing his power.