ominous vs unimposing

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. 

unimposing

adj
  • Not imposing; not grand or magnificent; modest. 

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