grand dukedom vs sultan

grand dukedom

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

sultan

noun
  • The holder of a secular office, formally subordinate to, but de facto the power behind the throne of, the caliph. 

  • A hereditary ruler in various Muslim states (sultanate), varying from petty principalities (as in Yemen), often vassal of a greater ruler, to independent realms, such as Oman, Brunei, Morocco (until 1956) or an empire such as the Turkish Ottoman Empire. 

  • A breed of chicken originating in Turkey, kept primarily in gardens for ornamental reasons. See: sultan (chicken) 

  • A variant of solitaire, played with two decks of cards. 

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