cathartic vs purging

cathartic

noun
  • A laxative. 

adj
  • Purgative; inducing mental or physical catharsis. 

  • That which releases emotional tension, especially after an overwhelming experience. 

purging

noun
  • The removal of digested waste: defecation; defecation induced by laxatives. 

  • Vomiting; vomiting induced by purgatives. 

  • A removal of undesirable people. 

  • The cleansing of a device by flushing it with water, steam, or some other liquid or gas. 

  • The removal of excess humors through bloodletting, induced vomitting, etc. 

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