roughness vs stiffness

roughness

noun
  • The property of being rough, coarseness. 

  • A measure of how rough something is, such as a surface 

  • Abundance, especially of food. 

  • Roughage; coarse fodder. 

  • Something that is rough; a rough spot. 

stiffness

noun
  • rigidity or a measure of rigidity. 

  • inelegance; a lack of relaxedness. 

  • inflexibility or a measure of inflexibility. 

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

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