cast iron vs spartan

cast iron

adj
  • Durable; tough; resilient. 

  • Inflexible or without exception. 

  • Made of cast iron. 

noun
  • A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould. 

spartan

adj
  • Resolute in the face of danger or adversity. 

  • Lacking in decoration and luxury. 

  • Austere, frugal, characterized by self-denial. 

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