Duke/duːk/ Definition 1 of 3Pro Tip 1/3Peerage Hierarchy Understand that a duke is high in the noble hierarchy, just below royalty. At official events, the duke was seated among other high-ranking nobles. Pro Tip 2/3Hereditary Position Many dukes inherit their title, which passes from parent to child in noble families. The duke's eldest son will inherit the dukedom one day. Pro Tip 3/3Addressing Dukes Use 'Your Grace' or 'Duke' when addressing dukes formally. Good morning, Your Grace. How may I assist you today?