cast iron vs criminal

cast iron

adj
  • Inflexible or without exception. 

  • Made of cast iron. 

  • Durable; tough; resilient. 

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

criminal

adj
  • Abhorrent or very undesirable. 

  • Against the law; forbidden by law. 

  • Guilty of breaking the law. 

  • Of or relating to crime or penal law. 

noun
  • A person who is guilty of a crime, notably breaking the law. 

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