baroness vs grand dukedom

baroness

noun
  • A woman holding a baronial title in her own right; a female ruler of a barony. 

  • The wife of a baron. 

grand dukedom

noun
  • The title of grand duke or grand duchess, with its pertaining privileges and obligations; contrast grand duchy. 

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