inert vs phlegmatic

inert

adj
  • Sluggish or lethargic. 

  • Unable to move or act; inanimate. 

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

  • Having no therapeutic action. 

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

noun
  • A substance that does not react chemically. 

phlegmatic

adj
  • Not easily excited to action or passion; calm; sluggish. 

  • Generating, causing, or full of phlegm. 

noun
  • One who has a phlegmatic disposition. 

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