annulus(redirected from Annular region)
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n. pl. an·nu·lus·es or an·nu·li (-lī′)
1. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.
a. A ring or group of thick-walled cells around the sporangia of many ferns that functions in spore release.
b. The ringlike remains of a broken partial veil, found around the stipes of certain mushrooms.
3. Mathematics The figure bounded by and containing the area between two concentric circles.
[Latin ānulus, ring, diminutive of ānus.]
n, pl -li (-ˌlaɪ) or -luses
1. (Mathematics) the area between two concentric circles
2. a ring-shaped part, figure, or space
[C16: from Latin, variant of ānulus ring]
an•nu•lus(ˈæn yə ləs)
n., pl. -li (-ˌlaɪ)
1. a ringlike part, band, or space; ring.
2. the space between two concentric circles on a plane.
3. the veil remnant on a mushroom stalk.
4. a growth ring, as the annual ring of a tree trunk, that can be used to estimate age.
[1555–65; < Latin, variant of ānulus=ān(us) ring + -ulus -ule]
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|Noun||1.||annulus - a toroidal shape; "a ring of ships in the harbor"; "a halo of smoke"|
fairy circle, fairy ring - a ring of fungi marking the periphery of the perennial underground growth of the mycelium
toroid - the doughnut-shaped object enclosed by a torus
|2.||annulus - (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar|
Fungi, fungus kingdom, kingdom Fungi - the taxonomic kingdom including yeast, molds, smuts, mushrooms, and toadstools; distinct from the green plants
partial veil - membrane of the young sporophore of various mushrooms extending from the margin of the cap to the stem and is ruptured by growth; represented in mature mushroom by an annulus around the stem and sometimes a cortina on the margin of the cap