ominous vs unlucky

ominous

adj
  • Specifically, giving indication of a coming ill; being an evil omen 

  • Of or pertaining to an omen or to omens; being or exhibiting an omen; significant. 

unlucky

adj
  • Bringing ill luck. 

  • Having ill luck. 

  • Inauspicious. 

  • Unfortunate, marked by misfortune. 

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