sultana vs viscountess

sultana

noun
  • A wife or mistress of a sultan. 

  • 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. 

viscountess

noun
  • The wife of a viscount. 

  • A woman holding the rank of viscount in her own right. 

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