castellan vs seneschal

castellan

noun
  • The governor or caretaker entrusted to oversee a castle or keep for its lord. 

seneschal

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

  • 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. 

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