curious vs impassive

curious

adj
  • Containing or pertaining to trivalent curium. 

  • Tending to ask questions, or to want to explore or investigate; inquisitive; (with a negative connotation) nosy, prying. 

  • Leading one to ask questions about; somewhat odd, out of the ordinary, or unusual. 

  • Caused by curiosity. 

impassive

adj
  • Having, or revealing, no emotion. 

  • Still or motionless. 

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