empress vs heritor

empress

noun
  • The wife or widow of an emperor or equated ruler. 

  • The third trump or major arcana card of most tarot decks. 

  • The female monarch (ruler) of an empire. 

  • A female chimpanzee. 

  • A deciduous tree, Paulownia tomentosa 

heritor

noun
  • A person who inherits; an heir or heiress. 

  • A proprietor or landholder in a parish. 

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