breech vs buttocks

breech

noun
  • The part of a cannon or other firearm behind the chamber. 

  • A breech birth. 

  • A garment whose purpose is to cover or clothe the buttocks. 

  • The external angle of knee timber, the inside of which is called the throat. 

verb
  • To fit or furnish with a breech. 

  • To fasten with breeching. 

adv
  • With the hips coming out before the head. 

adj
  • Born, or having been born, breech. 

buttocks

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