caesar vs crown princess

caesar

noun
  • emperor, ruler, dictator 

  • Any agaric mushroom of the genus Amanita, section Amanita sect. Caesareae. 

crown princess

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

  • The wife of a crown prince. 

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