duke vs grand duchess

duke

noun
  • A grand duke. 

  • The male ruler of a duchy (female equivalent: duchess). 

  • A fist. 

  • The sovereign of a small state. 

  • A high title of nobility; the male holder of a dukedom. 

  • Any of various nymphalid butterflies of the Asian genera Bassarona and Dophla. 

verb
  • To hit or beat with the fists. 

  • To give cash to; to give a tip to. 

grand duchess

noun
  • The wife or widow of a grand duke. 

  • A daughter or granddaughter of a sovereign (czar or later emperor) of the Russian Empire or a pretender to the throne thereof. 

  • The wife of a grand prince. 

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