hardy vs pig iron

hardy

noun
  • A blacksmith's fuller or chisel, having a square shank for insertion into a square hole in an anvil, called the hardy hole. 

  • Anything, especially a plant, that is hardy. 

adj
  • Impudent. 

  • Having rugged physical strength; inured to fatigue or hardships. 

  • Able to survive adverse growing conditions. 

  • Brave and resolute. 

pig iron

noun
  • A type of crude, brittle iron shaped like a block, unsuitable for working but suitable for casting, commonly used as an industrial raw material. 

  • crude iron 

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