oligarch vs sultana

oligarch

noun
  • A member of an oligarchy; someone who is part of a small group that runs a country. 

  • A very wealthy business owner who wields political power. 

  • A protoplanet formed during oligarchic accretion. 

sultana

noun
  • A female ruler of a sultanate. 

  • An old form of necklace. 

  • A pale yellow raisin made from a seedless grape. 

  • A type of viol, a cither viol. 

  • A wife or mistress of a sultan. 

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