I·ron a.
 1. Of, or made of iron; consisting of iron; as, an iron bar, dust.
 2. Resembling iron in color; as, iron blackness.
 3. Like iron in hardness, strength, impenetrability, power of endurance, insensibility, etc.; as:
 (a) Rude; hard; harsh; severe.
    Iron years of wars and dangers.   --Rowe.
    Jove crushed the nations with an iron rod.   --Pope.
 (b) Firm; robust; enduring; as, an iron constitution.
 (c) Inflexible; unrelenting; as, an iron will.
 (d) Not to be broken; holding or binding fast; tenacious. “Him death's iron sleep oppressed.”
 Note: ☞ Iron is often used in composition, denoting made of iron, relating to iron, of or with iron; producing iron, etc.; resembling iron, literally or figuratively, in some of its properties or characteristics; as, iron-shod, iron-sheathed, iron-fisted, iron-framed, iron-handed, iron-hearted, iron foundry or iron-foundry.
 Iron age. (a) Myth. The age following the golden, silver, and bronze ages, and characterized by a general degeneration of talent and virtue, and of literary excellence. In Roman literature the Iron Age is commonly regarded as beginning after the taking of Rome by the Goths, A. D. 410. (b) Archæol. That stage in the development of any people characterized by the use of iron implements in the place of the more cumbrous stone and bronze.
 Iron cement, a cement for joints, composed of cast-iron borings or filings, sal ammoniac, etc.
 Iron clay Min., a yellowish clay containing a large proportion of an ore of iron.
 Iron cross, a German, and before that Prussian, order of military merit; also, the decoration of the order.
 Iron crown, a golden crown set with jewels, belonging originally to the Lombard kings, and indicating the dominion of Italy. It was so called from containing a circle said to have been forged from one of the nails in the cross of Christ.
 Iron flint Min., an opaque, flintlike, ferruginous variety of quartz.
 Iron founder, a maker of iron castings.
 Iron foundry, the place where iron castings are made.
 Iron furnace, a furnace for reducing iron from the ore, or for melting iron for castings, etc.; a forge; a reverberatory; a bloomery.
 Iron glance Min., hematite.
 Iron hat, a headpiece of iron or steel, shaped like a hat with a broad brim, and used as armor during the Middle Ages.
 Iron horse, a locomotive engine. [Colloq.]
 Iron liquor, a solution of an iron salt, used as a mordant by dyers.
 Iron man Cotton Manuf., a name for the self-acting spinning mule.
 Iron mold or Iron mould, a yellow spot on cloth stained by rusty iron.
 Iron ore Min., any native compound of iron from which the metal may be profitably extracted. The principal ores are magnetite, hematite, siderite, limonite, Göthite, turgite, and the bog and clay iron ores.
 Iron pyrites Min., common pyrites, or pyrite. See Pyrites.
 Iron sand, an iron ore in grains, usually the magnetic iron ore, formerly used to sand paper after writing.
 Iron scale, the thin film which forms on the surface of wrought iron in the process of forging. It consists essentially of the magnetic oxide of iron, Fe3O4.
 Iron works, a furnace where iron is smelted, or a forge, rolling mill, or foundry, where it is made into heavy work, such as shafting, rails, cannon, merchant bar, etc.
 iron man
      n : a strong man of exceptional physical endurance [syn: ironman]