torus

noun8

1. •
   The standard representation of such a space in 3-dimensional Euclidean space: a surface or solid formed by rotating a closed curve, especially a circle, about a line which lies in the same plane but does not intersect it (e.g. like a ring doughnut).
2. •
   A topological space which is a product of two circles.

   • A 4-variable Karnaugh map can be thought of, topologically, as being a torus.
3. •
   [in compounds] The product of the specified number of circles.
4. •
   A ring-shaped object, especially a large ring-shaped chamber used in physical research.
5. •
   A large convex molding, typically semicircular in cross section, which commonly projects at the base of a column and above the plinth.
6. •
   A rounded ridge of bone or muscle, especially one on the occipital bone.
7. •
   The end of the peduncle or flower stalk to which the floral parts (or in the Asteraceae, the florets of a flower head) are attached.
8. •
   The thickening of a membrane closing a wood-cell pit (as of gymnosperm tracheids) having the secondary cell wall arched over the pit cavity.