duff vs unsound

duff

adj
  • Worthless; not working properly, defective. 

verb
  • To hit the ground behind the ball. 

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

noun
  • 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. 

  • The buttocks. 

unsound

adj
  • Not good, unreliable. 

  • Not whole, not solid, defective. 

  • Infirm, diseased. 

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