crown princess vs heritor

crown princess

noun
  • The heiress apparent to the throne in a royal or imperial monarchy. 

  • The wife of a crown prince. 

heritor

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

  • A proprietor or landholder in a parish. 

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