discoloration vs unsoundness

discoloration

noun
  • The act of discoloring, or the state of being discolored; alteration of hue or appearance. 

  • A discolored spot; a stain. 

unsoundness

noun
  • The state of being unsound. 

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