dastard vs pigeon-livered

dastard

adj
  • Meanly shrinking from danger, cowardly, dastardly. 

noun
  • A malicious coward; a dishonorable sneak. 

verb
  • To dastardize. 

pigeon-livered

adj
  • cowardly 

How often have the words dastard and pigeon-livered occurred in a corpus of books? (source: Google Ngram Viewer )