铁块 (tiě kuài) literally means 'iron block' — a solid, dense piece of metallic iron, typically unshaped or roughly cast. The first character 铁 (tiě) means 'iron', referring to the chemical element Fe and commonly used for iron-based materials; the second character 块 (kuài) is a general measure word for solid, lump-like objects, but when compounded as a noun, it signifies a 'block', 'chunk', or 'mass'. Together, 铁块 refers specifically to a physical, tangible block of iron — not an abstract concept or alloy like steel (钢), though in casual speech it may loosely include iron-rich alloys.

This term appears in industrial, metallurgical, educational, and everyday contexts — for example, describing raw material in a foundry, a physics demonstration on density or magnetism, or even a metaphorical weight in literature. It is neutral in register and more precise than generic terms like 金属 (jīnshǔ, 'metal') or 物体 (wùtǐ, 'object'). Unlike 钢块 (gāng kuài, 'steel block'), 铁块 emphasizes pure or nearly pure iron content and often implies heaviness, hardness, and magnetic properties.