The Collaborative International Dictionary of English v.0.48:

Propretor \Pro*pre"tor\, n. [L. propraetor; pro for, before +
   praetor a pretor.] (Rom. Antiq.)
   A magistrate who, having been pretor at home, was appointed
   to the government of a province. [Written also
   propr[ae]tor.]
   [1913 Webster]