/ ˈdəʊfæ͂; -fæn; NAmE ˈdoʊ-/ noun
( old use ) the oldest son of the king of France
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WORD ORIGIN
French , from the family name of the lords of the Dauphiné, an area of SE France: ultimately a nickname meaning dolphin. In 1349 the future Charles V acquired the lands and the title; when king he ceded them to his eldest son, establishing the practice of passing both title and lands to the Crown prince.