noun

annulus

Annulus (noun) means a ring- or donut-shaped area, object, or structure.

noun

A ring- or donut-shaped area, object, or structure.

A ring of fibrous tissue; specifically (cardiology), such a ring around an opening of a heart valve, to which the valve leaflets and muscle fibres of the atria and ventricles are attached; an annulus fibrosus cordis.

A ring of light in a celestial body, especially when caused by an annular eclipse (for example, when the Sun and Moon are in line with the Earth, but the Moon does not completely cover the Sun's disc).

A structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for spore dispersal; specifically, in a fern: a structure around about two-thirds of the sporangium consisting of differentially thick-walled cells which dry and distort the sporangium; and in a moss: a complete ring of cells around the tip of the sporangium which dissolves to cause the tip to detach.

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Etymology

Learned borrowing from Medieval Latin ānnulus, a misspelling of Latin ānulus (“ring, especially one worn on a finger”), from ānus (“ring”) (possibly from Proto-Indo-European *h₁eh₂-n-o- (“ring”), from an uncertain root) + -ulus (diminutive suffix). The plural form annuli is a learned borrowing from Medieval Latin ānnulī.

Rhymes for annulus

Romulus calculus stimulus homunculus

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Frequently asked questions

What is the meaning of annulus?

"annulus" (noun) means a ring- or donut-shaped area, object, or structure.

What are the different meanings of annulus?

"annulus" has 3 main meanings: 1. A ring- or donut-shaped area, object, or structure; 2. A ring of fibrous tissue; specifically (cardiology), such a ring around an opening of a heart valve, to which the valve leaflets and muscle fibres of the atria and ventricles are attached; an annulus fibrosus cordis; 3. A ring of light in a celestial body, especially when caused by an annular eclipse (for example, when the Sun and Moon are in line with the Earth, but the Moon does not completely cover the Sun's disc).