What is the meaning of Dauphin?

The eldest son of the king of France. Under the Valois and Bourbon dynasties, the Dauphin of France, generally shortened to Dauphin, was heir apparent to the throne of France. The title derived from the main title of the Dauphin, Dauphin of Viennois.

An eldest son.

dauphin (the eldest son of the king of France and heir apparent to the French throne)

dolphin

dolphin; the animal used as a charge

successor, dauphin

runner-up

dauphin (eldest son of the king of France)

Source: wiktionary.org