chills vs rigor

chills

noun
  • A feeling of being cold, a symptom of many conditions. 

  • A biological response to being tickled; being cold; or experiencing fear, euphoria or sexual arousal in which the person forms goose bumps. 

rigor

noun
  • A feeling of cold with shivering accompanied by a rise in body temperature. 

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