carapace vs middle

carapace

noun
  • in figurative use 

  • A hard protective covering of bone or chitin, especially one which covers the dorsal portion of an animal. 

middle

noun
  • A centre, midpoint. 

  • The part between the beginning and the end. 

  • The middle stump. 

  • The central part of a human body; the waist. 

  • The middle voice. 

adj
  • Pertaining to the middle voice. 

  • Located in the middle; in between. 

  • Central. 

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