from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.
- n. A ring or group of thick-walled cells around the sporangia of many ferns that functions in spore release.
- n. The ringlike remains of a broken partial veil, found around the stipes of certain mushrooms.
- n. Mathematics The figure bounded by and containing the area between two concentric circles.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A ring- or donut-shaped area or structure.
- n. The region in a plane between two concentric circles of different radius.
- n. Any topological space homeomorphic to the region in a plane between two concentric circles of different radius.
- n. The ring of the sun not covered by the moon in an annular solar eclipse.
- n. Structure in a fern that consists of differentially thick-walled cells on a sporangium that bend and distort as a result of drying.
- n. The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.
- n. The space contained between the centre well bore and any external tubing. Sometimes used for separated gas flow.
from the GNU version of the Collaborative International Dictionary of English
- n. A ring; a ringlike part or space.
- n. A space contained between the circumferences of two circles, one within the other.
- n. The solid formed by a circle revolving around a line which is the plane of the circle but does not cut it.
- n. Ring-shaped structures or markings, found in, or upon, various animals.
from The Century Dictionary and Cyclopedia
- n. A ring-like space or area contained between the circumferences of two concentric circles.
- n. In anatomy, a ring-like part, opening, etc.: used in Latin phrases.
- n. (See below.) In botany: The elastic ring which surrounds the spore-case of most ferns.
- n. In mosses, an elastic ring of cells lying between the lid and the base of the peristome or orifice of the capsule.
- n. In fungi, the slender membrane surrounding the stem in some agarics after the cap has expanded.
- n. In zoology: A thin chitinous ring which encircles the mantle in the Tetrabranchiata, connecting chitinous patches of the mantle into which the shell-muscles are inserted.
- n. In entomology, a narrow encircling band, generally of color; sometimes a raised ring.
- n. In astronomy, the ring of light seen about the edge of the moon in an annular eclipse of the sun. See annular eclipse, under annular.
- n. In the Equisetaceæ, the sheath below the spike formed by the union of the bases of the leaves.
- n. In diatoms, the rim of silex formed within the frustules of some genera.
- n. The fleshy rim of the corolla in milkweeds.
- n. One of the external subdivisions of the body of a leech, resembling a segment of the body of an earthworm.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a toroidal shape
- n. (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
Latin ānulus, ring, diminutive of ānus.(American Heritage® Dictionary of the English Language, Fourth Edition)