Dauphin means dolphin. It comes from the coat of arms of the French county of Viennois in southeastern France. 
The county was willed to the French crown in 1349 on the condition that it not be merged with France, it become the personal fief of the heir to the French Crown and that the heir be referred to as Le Dauphin. 
Hope this helps.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)