torus

n. ring; rounded projection or swelling

In geometry, a torus (pl. tori) is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle, which does not touch the circle. Examples of tori include the surfaces of doughnuts and inner tubes. A circle rotated about a chord of the circle is called a torus in some contexts, but this is not a common usage in mathematics. The shape produced when a circle is rotated about a chord resembles a round cushion. Torus was the Latin word for a cushion of this shape.
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Torus /to·rus/ pl. to´ri [L.] a swelling or bulging projection. to·rus n. pl. to·ri A bulging or rounded projection or swelling, such as is caused [more]Torus - Community and Resources

Noun
1. a ring-shaped surface generated by rotating a circle around an axis that does not intersect the circle
(synonym) toroid
(hypernym) round shape
2. commonly the lowest molding at the base of a column
(synonym) tore
(hypernym) molding, moulding

n. torus, ring; rounded projection or swelling