Iron is a strong, heavy metal that's been crucial to human civilization for thousands of years. When heated until glowing, iron can be hammered into different shapes: swords, horseshoes, nails, bridges, or the steel frames of skyscrapers. Before iron, people made tools from softer metals like bronze or copper, which couldn't hold an edge as well or support heavy weights.

The word also refers to a household device used to smooth wrinkles from clothes. A clothing iron has a flat metal bottom that heats up. When you press it against wrinkled fabric, the heat and pressure make the wrinkles disappear.

Your body needs iron too. It's an essential mineral that helps your blood carry oxygen to every part of your body. Without enough iron, you'd feel tired and weak. You get iron by eating foods like red meat, spinach, and beans.

As an adjective, iron describes something extremely strong or unbreakable. A coach with iron discipline never lets the team slack off. Someone with an iron will doesn't give up, no matter how hard things get. When you say someone rules with an iron fist, you mean they control things strictly and firmly, allowing no disagreement.