In maths, a polyhedron is just a three-dimensional solid which consists of a set of polygons, usually joined at their edges. The word derives from the Greek poly (many) plus the Indo-European hedron (seat). The plural of polyhedron is "polyhedra" (or sometimes "polyhedrons").
Polyhedrons are solids with flat faces. Any 3-dimensional solid is a polyhedron if all of its sides are flat. Examples of real-world polyhedrons include soccer balls, prisms, bricks, houses, and pyramids. All of these shapes have flat sides.
