retromingent vs treacherous

retromingent

adj
  • Cowardly. 

  • That urinates backwards; also used of such urination. 

treacherous

adj
  • Deceitful; inclined to betray. 

  • Unreliable; dangerous. 

  • Exhibiting treachery. 

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