frigidity vs pyrexia

frigidity

noun
  • The state of being frigid; coldness; lack of heat. 

  • Coldness of feeling, manner or quality; lack of ardor, animation or vivacity. 

  • Lack of natural heat and vigor of body; impotency. 

pyrexia

noun
  • Fever. 

  • Trench fever. 

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