inflexibleness vs stiffness

inflexibleness

noun
  • The quality or state of being inflexible 

  • Obstinacy of will or temper; firmness of purpose that will not yield to importunity or persuasion; unbending pertinacity. 

stiffness

noun
  • inflexibility or a measure of inflexibility. 

  • inelegance; a lack of relaxedness. 

  • rigidity or a measure of rigidity. 

  • muscular tension due to unaccustomed or excessive exercise or work; soreness. 

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