impactive vs portentous

impactive

adj
  • Of, pertaining to, possessing, or caused by impact. 

portentous

adj
  • Of momentous or ominous significance. 

  • Ominously prophetic. 

  • Puffed up with vanity. 

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