cast iron vs stalwart

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. 

stalwart

adj
  • Courageous. 

  • Firmly or solidly built. 

  • Determined; staunch. 

noun
  • One who is dependable. 

  • One who has a strong build. 

  • One who firmly supports a cause. 

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