caesar vs rex

caesar

noun
  • emperor, ruler, dictator 

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

rex

noun
  • An animal which has a genetic recessive variation that causes the guard hairs to be very short or fully lacking. 

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