A cube is called a hexahedron because it is a polyhedron that has 6 (hexa- means 6) faces.
Instructions: In "spin" mode it freely spins and will respond to your mouse. In "drag" mode it stops spinning and you can use your mouse to move it. If you cannot see the animation at all, you will need to install "Flash Player".
Note: If you have more than one hexahedron they are called hexahedra
(and the plural of cube is cubes of course!)
Cubes make nice 6-sided dice, because they are regular in shape, and each face is the same size.
In fact, you can make fair dice out of all of the Platonic Solids.