annulus

American  

[an-yuh-luhs] / ˈæn jə ləs /

noun

• annuli,
  plural
• annuluses
  plural

1. a ring; a ringlike part, band, or space.

2. Geometry. the space between two concentric circles on a plane.

3. the veil remnant on a mushroom stalk.

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

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annulus British  

/ ˈænjʊləs /

noun

1. the area between two concentric circles

2. a ring-shaped part, figure, or space

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annulus Scientific  

/ ăn′yə-ləs /

• annuluses
  plural

1. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.

2. 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.

3. 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.

4. The figure bounded by and containing the area between two concentric circles.

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Other Word Forms

Noun Inflected Forms

• annuli
  plural
• annuluses
  plural

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Etymology

Origin of annulus

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

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Example Sentences

See Examples For:

annulus annuli

It's called an annular eclipse because just a thin ring, or annulus, of light remains visible.

From BBC ● Oct. 10, 2023

The circular annulus sector R bounded by the circles 4x2 + 4y2 = 1 and 9x2 + 9y2 = 64, the line x = y 3, and the y-axis is shown in the following figure.

From Textbooks ● Mar. 30, 2016

The red primer annulus makes me lean towards Iran, but this example could quite easily have come from either country.

From New York Times ● Nov. 7, 2012

Its tubercles and soft tissues were inflamed, and the annulus fibrosus of its disks was the color of bad teeth.

From The New Yorker ● Feb. 28, 2011

This species very closely resembles Amanita verna, from which it can be distinguished by its large, persistent annulus, the elongated downward-tapering bulb of its stem, and, especially, by its elliptical spores.

From The Mushroom, Edible and Otherwise Its Habitat and its Time of Growth by Miron Elisha Hard

In some the general hue is orange brown with obscure annuli; the arrangement of the hair is distichous or in two rows.

From Natural History of the Mammalia of India and Ceylon by Robert Armitage Sterndale

It looks as though these partially-formed annuli must be prevented by their acquired motions from approaching even very near to the still-irregular body they surround.

From Essays: Scientific, Political, & Speculative, Vol. I by Herbert Spencer

Aging white-tailed deer by annuli in the cementum of the first incisor.

From Ecological Studies of the Timber Wolf in Northeastern Minnesota by L. D. Frenzel

The jus annuli aurei, or right of wearing a gold ring, originally a military distinction, became a senatorial privilege, which was afterwards extended to the knights and gradually to other classes.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 4 "Coquelin" to "Costume" by Various

In the Gnathobdellidae the prevailing number of annuli to a segment is five; but here again the number is often increased, and Trocheta has no less than eleven.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" by Various

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