backside vs breech

backside

noun
  • A person's buttocks. 

  • Used other than figuratively or idiomatically: see back, side. 

  • The back side of an estate: the backyard and outbuildings behind a main house, especially (UK dialect, euphemistic) an outhouse. 

  • The reverse or opposite of anything. 

adj
  • Used other than figuratively or idiomatically: see back, side. 

  • Approaching an obstacle backward 

breech

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

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

  • A breech birth. 

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

adj
  • Born, or having been born, breech. 

verb
  • To fit or furnish with a breech. 

  • To fasten with breeching. 

adv
  • With the hips coming out before the head. 

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