cautionary vs portentous

cautionary

adj
  • Serving to caution or warn; admonitory 

  • Serving to ward off; preventive 

portentous

adj
  • Of momentous or ominous significance. 

  • Ominously prophetic. 

  • Puffed up with vanity. 

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