indigestible vs unhappy

indigestible

adj
  • Difficult to accept; unpalatable. 

  • Difficult or impossible to digest. 

noun
  • Anything that is difficult to digest. 

unhappy

adj
  • Not satisfied; unsatisfied. 

  • Not happy; sad. 

noun
  • An individual who is not happy. 

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