margrave vs marquis

margrave

noun
  • A hereditary ruling prince in certain feudal states of the Holy Roman Empire and elsewhere; the titular equivalent became known as marquis or marquess. 

  • A feudal era military-administrative officer of comital rank in the Carolingian empire and some successor states, originally in charge of a border area. 

marquis

noun
  • A nobleman in England, France, and Germany, of a rank next below that of duke, but above a count. Originally, the marquis was an officer whose duty was to guard the marches or frontiers of the kingdom. The office has ceased, and the name is now a mere title conferred by letters patent or letters close. 

  • Any of various nymphalid butterflies of the Asian genus Bassarona (or Euthalia). 

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