An alloy of iron with small amounts of carbon; widely used in construction; mechanical properties can be varied over a wide range WordNet 3.0 & Open English WordNet

Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Wikipedia

Metal alloy that is composed principally of iron and carbon. Wikipedia Disambiguation

Industry that deals with the processing of iron. OmegaWiki

Any of various alloys based on iron containing carbon (usually 0.1-0.7 per cent) and often small quantities of other elements such as phosphorus, sulphur, manganese, chromium, and nickel. Steels exhibit a variety of properties, such as strength, machinability, malleability, etc., depending on their composition and the way they have been treated. OmegaWiki