What does the Latin “prorex” mean in reference to Louis II de Bourbon?

Question

On the cover of the Paris edition of Raymund Martin's Pugio Fidei, it states,

AD SERENISSIMUM REGIÆ STIRPIS PRIMUM PRINCIPEM LUDOVICUM BORBONIUM CONDÆUM BURDEGALÆ ET AQUITANIÆ PROREGEM OPTATISSIMUM.

As one can see, this "Ludovicum Borbonium," whom I believe to be Louis II de Bourbon, is is referred to by the Latin title Proregem (or Prorex in the nominative case). What exactly does this Latin title mean in reference to Louis II of Bourbon? What would have been the French equivalent? What was his royal position?

Answer 1

"Proregem" apparently can be translated as "viceroy" (similarly to the Roman proconsul or legate pro Augusti). Overall I'd understand the sentence as saying that Conde was the governor of Brugundy and Aquitaine (since I do not recall a former viceregal position in France). Some googling failed to find a source about the political dispensation of Burgundy in the 17th century, so I'll stay with "governor".