Annulus
Annulus ({not transcribed}) , noun
[Latin]
1.
A ring; a ringlike part or space.
2.
(a) (Geometry) A space contained between the circumferences of two circles, one within the other.
(b)
(Geometry) The solid formed by a circle revolving around a line which is the plane of the circle but does not cut it.
3.
(Zoology) Ring-shaped structures or markings, found in, or upon, various animals.