crown princess vs inheritor

crown princess

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

  • The wife of a crown prince. 

inheritor

noun
  • Someone who inherits something; an heir. 

  • A class, etc. that derives from another code element through inheritance. 

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