roughness vs similarity

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. 

similarity

noun
  • A transformation that preserves angles and the ratios of distances 

  • The property of two matrices being similar. 

  • Closeness of appearance to something else. 

  • The relation of sharing properties. 

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