A slab is a flat, usually rectangular piece of stone or concrete that is used for various purposes. It can refer to a large, thick piece of something, such as a cut of meat or a slice of bread. In construction terms, it refers to a thick, heavy piece of material, typically made from poured concrete, which serves as a foundation or floor. A slab can also be used in reference to a flat area of land or snow, where nothing grows or accumulates.