diehard vs indigestible

diehard

adj
  • Unreasonably or stubbornly resisting change. 

  • Fanatically opposing progress or reform. 

  • Complete; having no opposite opinion of anything in a particular topic of one's values; thorough of in one's beliefs. 

noun
  • A person with such an attitude. 

indigestible

adj
  • Difficult to accept; unpalatable. 

  • Difficult or impossible to digest. 

noun
  • Anything that is difficult to digest. 

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