backside vs longhouse

backside

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

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

  • The reverse or opposite of anything. 

  • A person's buttocks. 

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

  • Approaching an obstacle backward 

longhouse

noun
  • A long communal housing of the Iroquois and some other American Indians, the Malaysians, the Indonesians, the Vikings, and many other peoples. 

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