indigestible vs inert

indigestible

adj
  • Difficult or impossible to digest. 

  • Difficult to accept; unpalatable. 

noun
  • Anything that is difficult to digest. 

inert

adj
  • Unable to move or act; inanimate. 

  • Sluggish or lethargic. 

  • In chemistry, not readily reacting with other elements or compounds. 

  • Having no therapeutic action. 

noun
  • A substance that does not react chemically. 

verb
  • To fill with an inert gas to reduce the risk of explosion. 

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