byword vs middle name

byword

noun
  • Someone or something that stands as an example (i.e. metonymically) for something else, by having some of that something's characteristic traits. 

  • A nickname or epithet. 

  • A characteristic word or expression; a word or phrase associated with a person or group. 

  • A proverb or proverbial expression, common saying; a frequently used word or phrase. 

  • An object of notoriety or contempt, scorn or derision. 

middle name

noun
  • A trait, activity, or action closely associated with or aptly describing a person. 

  • A name between the first given name and the family name or surname; a second or subsequent given name. 

  • One's mother's maiden name. 

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