refractory vs turbulent

refractory

adj
  • Obstinate and unruly; strongly opposed to something. 

  • Not affected by great heat. 

  • Difficult to treat. 

  • Incapable of registering a reaction or stimulus. 

noun
  • A material or piece of material, such as a brick, that has a very high melting point. 

turbulent

adj
  • violently disturbed or agitated; tempestuous, tumultuous 

  • being in, or causing, disturbance or unrest 

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