dingo vs yellow back

dingo

noun

  • A cowardly or otherwise despicable person. 

  • A wild dog native to Australia (Canis familiaris, Canis familiaris dingo, Canis dingo, or Canis lupus dingo). 

yellow back

noun

  • A coward. 

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