Collins COBUILD Advanced Learner's English Dictionary - cast iron

1. Cast iron is iron which contains a small amount of carbon. It is hard and cannot be bent so it has to be made into objects by casting. Made from cast iron, it is finished in graphite enamel. ...the cast-iron chair legs. N-UNCOUNT 2. A cast-iron guarantee or alibi is one that is absolutely certain to be effective and will not fail you. They would have to offer cast-iron guarantees to invest in long-term projects. ADJ: usu ADJ n