[{"Bold_text": "noun", "List Items": ["an alloy of iron, carbon, and other elements, cast as a soft and strong, or as a hard and brittle, iron, depending on the mixture and methods of molding."]}, {"Bold_text": "adjective", "List Items": ["made of cast iron.", "not subject to change or exception:a cast-iron rule.", "hardy:a cast-iron stomach."]}]