annulus

[ an-yuh-luhs ]

noun,plural an·nu·li

[an-yuh-lahy], /ˈæn yəˌlaɪ/, an·nu·lus·es.

a ring; a ringlike part, band, or space.
Geometry. the space between two concentric circles on a plane.

the veil remnant on a mushroom stalk.
a growth ring, as on the cross section of a tree trunk, that can be used to estimate age.

Origin of annulus

1555–65; <Latin, variant of ānulus, equivalent to ān(us) ring + -ulus-ule

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use annulus in a sentence

In some the general hue is orange brown with obscure annuli; the arrangement of the hair is distichous or in two rows.
Natural History of the Mammalia of India and Ceylon | Robert A. Sterndale
This phrase is somewhat obscure: "annuli ferrei sicut solebat fieri in cista Norensi."
The Chronicle of Jocelin of Brakelond: A Picture of Monastic Life in the Days of Abbot Samson | Jocelin de Brakelond
Such annuli or streams would probably each furnish an immense number of meteor-asteroids.
Meteoric astronomy: | Daniel Kirkwood
This corresponds to the usual presence (in the Rhynchobdellidae) of three annuli to each segment.
Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 | Various
As remarked, the prevalent number of annuli to a segment is three in the Rhynchobdellidae.
Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 | Various

British Dictionary definitions for annulus

annulus

/ (ˈænjʊləs) /

nounplural -li (-ˌlaɪ) or -luses

the area between two concentric circles
a ring-shaped part, figure, or space

Origin of annulus

C16: from Latin, variant of ānulus ring

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for annulus

annulus

[ ăn′yə-ləs ]

Plural annuluses annuli (ăn′yə-lī′)

A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.
A ring or group of specialized cells around the sporangia of many ferns. By changing shape in response to variations in humidity, it breaks open the sporangium and then releases the spores with a whipping motion.

The ringlike remains of a membrane (called a veil), found around the stipes of certain basidiomycete mushrooms. The presence or absence of an annulus is often used to identify the species of an individual mushroom.
The figure bounded by and containing the area between two concentric circles.

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