ETYM Old Eng. iren, AS. îren, îsen, îsern; akin to Dutch ijzer, OS. îsarn, Old High Germ. îsarn, îsan, German eisen, Icel. îsarn, jârn, Swed. and Dan. jern, and perh. to Eng. ice; cf. Irish iarann, W. haiarn, Armor. houarn.
1. A heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood; SYN. Fe, atomic number 26.
2. Metal shackles; for hands or legs; SYN. irons, chain, chains.
3. A golfclub that has a relatively narrow metal head.
4. A rod used to brand live stock; SYN. branding iron.
A hard, malleable and ductile, silver-gray metallic element, symbol Fe (from Latin ferrum), atomic number 26, atomic weight 55.847. It is the fourth-most abundant element (the second-most abundant metal after aluminum) in the Earth’s crust. The central core of the Earth, the radius of which is believed to be 2,200 miles, is held to consist principally of iron with some nickel. When the amounts in the crust and core are combined, iron is probably the most abundant constituent element of the planet.
Although it almost always occurs in ores or as compounds, it sometimes occurs as a free metal (native metal), occasionally as fragments of iron or iron-nickel meteorites. Iron is the most common and most useful of all metals; it is strongly magnetic and is noted for becoming oxidized (rusted) in moist air. Iron is an essential component of hemoglobin, the molecule in the red blood cells, where it serves to transport oxygen to all parts of the body. Iron is the basis for steel, an alloy with carbon and other elements. Iron has been worked into tools by early peoples in both the Old World and the New and its use has persisted since the Iron Age of prehistory.