dau·phin /ˈdɔfən, ˈdo; ˌdoˈfæn/
  法國皇太子
  Dau·phin n.  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.
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  dauphin
       n : formerly, the eldest son of the King of France and direct
           heir to the throne