» Not to be confused with Taurus (disambiguation). In geometry, a torus (pl. tori)'s a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with and not touching the circle. Examples of tori include the surfaces of doughnuts and inner tubes. The solid contained by the surface's known as a toroid. A circle rotated about a chord of the circle's called a torus in some contexts, but this isn't a common usage in mathematics. The shape produced when… (More on Torus)