\Dau"phin\, n. [F. dauphin, prop., a dolphin, from L.
delphinus. See {Dolphin}. The name was given, for some reason
unexplained, to Guigo, count of Vienne, in the 12th century,
and was borne by succeeding counts of Vienne. In 1349,
Dauphiny was bequeathed to Philippe de Valois, king of
France, on condition that the heir of the crown should always
hold the title of Dauphin de Viennois.]
The title of the eldest son of the king of France, and heir
to the crown. Since the revolution of 1830, the title has
been discontinued.