annulus

[an-yuh-luh s]

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. 2018

Examples from the Web for annulus

Historical Examples of annulus

Armillate: with a ring or annulus of raised or different tissue.
Explanation of Terms Used in Entomology
John. B. Smith
Ring: a circle or annulus, usually margining a discolored spot.
Explanation of Terms Used in Entomology
John. B. Smith
The annulus is not persistent, and the gills are crowded and notched.
Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.
George Francis Atkinson
Some have referred the name to the Latin or Italian, annulus, or annello.
Ancient Armour and Weapons in Europe
John Hewitt
This was called the astronomical ring, annulus astronomicus.
Finger-Ring Lore
William Jones

British Dictionary definitions for annulus

annulus

noun plural -li (-ˌlaɪ) or -luses

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

Word Origin for 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

Word Origin and History for annulus

1560s, medical, from misspelling of Latin anulus "little ring, finger ring," a diminutive of anus (see anus).

annulus in Medicine

annulus

n. pl. an•nu•lus•es

A circular or ring-shaped structure.

annulus in Science

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.