The term "Your Majesty" is typically used to address a monarch, such as a king or queen. While princesses are members of the royal family, they are not addressed as "Your Majesty" unless they hold the title of Queen. Instead, they are often addressed using their royal title, such as "Her Royal Highness" followed by their name or "Princess [Name]." The exact form of address may vary depending on the country and its specific customs and protocols.