commonition vs omen

commonition

noun
  • advice; warning; instruction. 

omen

noun
  • A thing of prophetic significance. 

  • Something which portends or is perceived to portend either a good or evil event or circumstance in the future, or which causes a foreboding; a portent or augury. 

verb
  • To divine or predict from omens. 

  • To be an omen of. 

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