fearsome vs sinister

fearsome

adj
  • frightening, especially in appearance. 

sinister

adj
  • Evil or seemingly evil; indicating lurking danger or harm. 

  • On the left side of a shield from the wearer's standpoint, and the right side to the viewer. 

  • Inauspicious, ominous, unlucky, illegitimate (as in bar sinister). 

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