backside vs duff

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 

duff

noun
  • The buttocks. 

  • A mixture of coal and rock. 

  • A pudding-style dessert, especially one made with plums. 

  • The bits left in the bottom of the bag after the booty has been consumed, like crumbs. 

  • Something spurious or fake; a counterfeit, a worthless thing. 

  • An error. 

  • A stiff flour pudding, often with dried fruit, boiled in a cloth bag, or steamed. 

  • Fine and dry coal in small pieces, usually anthracite. 

  • Dough. 

  • Decaying vegetable matter on the forest floor. 

  • Coal dust, especially that left after screening or combined with other small, unsaleable bits of coal. 

adj
  • Worthless; not working properly, defective. 

verb
  • To hit the ground behind the ball. 

  • To alter the branding of stolen cattle; to steal cattle. 

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