phlegm vs serenity

phlegm

noun
  • Calmness of temperament, composure; also seen negatively, sluggishness, indifference. 

  • One of the four humors making up the body in ancient and mediaeval medicine; said to be cold and moist, and often identified with mucus. 

  • Viscid mucus produced by the body, later especially mucus expelled from the bronchial passages by coughing. 

  • A watery distillation, especially one obtained from plant matter; an aqueous solution. 

serenity

noun
  • The state of being serene; calmness; peacefulness. 

  • A lack of agitation or disturbance. 

  • A title given to a reigning prince or similar dignitary. 

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