roughness vs ruling class

roughness

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

  • Abundance, especially of food. 

  • Roughage; coarse fodder. 

  • The property of being rough, coarseness. 

  • Something that is rough; a rough spot. 

ruling class

noun
  • The social class of a given society that controls that society's political agenda, whether as formal aristocracy or party leadership or as an informal unit within democracies. 

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