burgomaster vs seneschal

burgomaster

noun
  • The mayor, or head magistrate, of a town in the Netherlands, Belgium, Germany and certain other countries. 

seneschal

noun
  • An officer of the crown in late medieval and early modern France who served as a kind of governor and chief justice of the royal court in Normandy and Languedoc. 

  • A steward, particularly (historical) one in charge of a medieval nobleman's estate. 

How often have the words burgomaster and seneschal occurred in a corpus of books? (source: Google Ngram Viewer )