dastardly vs retromingent

dastardly

adj
  • in the manner of a dastard; marked by cowardice; pusillanimous 

  • treacherous; given to backstabbing 

adv
  • In a cowardly or treacherous fashion. 

retromingent

adj
  • Cowardly. 

  • That urinates backwards; also used of such urination. 

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