Adjective

1. Made of cast iron.

   I use a castiron skillet for frying pancakes.

2. Durable; tough; resiliant.

   Ernest has a cast-iron constitution and never gets sick.

3. Inflexible or without exception.

   The school's cast-iron policy on admissions fees left no leeway for needy students.

Synonyms

Noun

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

   Cast iron is popular for cookware where an even heating temperature is important.