Preeminent

In Thlossian culture, the term "Preeminent" refers to the heir-apparent or heiress-apparent of a royal family. It is added as a suffix to the person's formal title. For example, Prince Goddard's full formal title is "Distinguished Lord Goddard Enthaen, Preeminent."

The terms "Prince Preeminent" or "Princess Preeminent" are sometimes used informally to refer to the eldest Prince or Princess of a royal family.