milky vs pigeon-livered

milky

adj
  • Cowardly. 

  • Containing a whitish liquid, juicy. 

  • Containing (an especially large amount of) milk. 

  • Of the black in an image, appearing as dark gray rather than black. 

  • Resembling milk in color, consistency, smell, etc.; consisting of milk. 

  • Immature, childish. 

pigeon-livered

adj
  • cowardly 

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