backside vs hindquarter

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 

hindquarter

noun
  • Human behind, butt. 

  • The hind biped (leg) of a quadruped, or all body parts situated behind the hind legs' trunk-attachment. 

  • Either rear half of a side of beef, mutton, veal, lamb or by extension from another edible mammal. 

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