Dauphin

Chamber's Twientieth Century Dictionary · 1908 · p. 28

daw′fin, n. the name given to the eldest son of the king of France, from 1349 down to 1830:— fem. Dau′phine . [O. Fr. daulphin (Fr. dauphin )—L. delphin us , a dolphin. From the dolphins in the crest of Viennois.]