countess vs potentate

countess

noun
  • A woman holding the rank of count or earl in her own right; a female holder of an earldom. 

  • The wife of a count or earl. 

potentate

noun
  • A powerful leader; a monarch; a ruler. 

  • A self-important person. 

  • A powerful polity or institution. 

  • Someone acting in an important role. 

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