refractory vs stiff-necked

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. 

stiff-necked

adj
  • Stubborn and arrogant. 

  • Having a stiff neck; suffering from torticollis 

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