n. | 1. | A ring; a ringlike part or space. |
2. | (Geom.) A space contained between the circumferences of two circles, one within the other. | |
3. | (Zool.) Ring-shaped structures or markings, found in, or upon, various animals. |
Noun | 1. | annulus - a toroidal shape; "a ring of ships in the harbor"; "a halo of smoke" |
2. | annulus - (Fungi) remnant of the partial veil that in mature mushrooms surrounds the lower part of the stem |