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.
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."
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.
As remarked, the prevalent number of annuli to a segment is three in the Rhynchobdellidae.
British Dictionary definitions for annulus
the area between two concentric circles
a ring-shaped part, figure, or space
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
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.