buttock vs dorsal

buttock

noun
  • Each of the two large fleshy halves of the posterior part of the body between the base of the back, the perineum and the top of the legs. 

  • The convexity of a ship behind, under the stern. 

dorsal

noun
  • Any of the longitudinal series of plates that encircle the body, excluding the ventral scales. 

  • A hanging, usually of rich stuff, at the back of a throne, altar, etc. 

  • A sound produced using the dorsum of the tongue. 

adj
  • Relating to the surface naturally inferior, as of a leaf. 

  • Relating to the surface naturally superior, as of a creeping hepatic moss. 

  • Having only one sharp side. 

  • Relating to the top surface of the foot or hand. 

  • Produced using the dorsum of the tongue. 

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