acerbate vs spleen

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

spleen

verb
  • To annoy or irritate. 

  • To remove the spleen, or, by extension, to gore. 

  • To excise or remove. 

  • To complain; to rail; to vent one's spleen. 

noun
  • A fit of immoderate laughter or merriment. 

  • In vertebrates, including humans, a ductless vascular gland, located in the left upper abdomen near the stomach, which destroys old red blood cells, removes debris from the bloodstream, acts as a reservoir of blood, and produces lymphocytes. 

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