Ans. In Geometry, the torus is defined as the doughnut-shaped, three -dimensional figure formed when the circle is rotated about a line in its plane, but not rotated through its axis. The word 'torus' is received from the Latin word meaning bulge. The plural form of the torus is tori. The term torus is sometimes referred to as an anchor.The most common example of the torus is an inner tube of a tire. Imagine, a circle lies in a plane, such that its diameter is perpendicular to its straight line. The figure that is formed, is a hollow circular tube known as a torus.