arse vs backside

arse

noun
  • Used in similes to express something bad or unpleasant. 

  • A stupid, pompous, arrogant, mean or despicable person. 

  • A person; the self; (reflexively) oneself or one's person, chiefly their body; (by extension) one's personal safety, or figuratively one's job, prospects, etc. 

verb
  • To be silly, act stupid or mess around. 

backside

noun
  • 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. 

  • A person's buttocks. 

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

  • Approaching an obstacle backward 

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