Alloy iron is a mixture of iron and other elements to enhance its properties. There are several words that can be used as synonyms for alloy iron, including steel, cast iron, wrought iron, and pig iron. Steel is an alloy iron with a small amount of carbon, making it stronger and more durable. Cast iron is a mixture of iron, carbon, and silicon that is easy to cast into shapes and has high heat resistance. Wrought iron is a pure form of iron that is malleable and can be forged into various shapes. Pig iron is a crude form of iron that has high carbon content and is primarily used in making steel. Each of these synonyms for alloy iron has unique properties and uses in various industries.