Background for annulus

annulus

/ˈænjələs/ /ˈænjʊləs/

Illustration annulus - Image 1

Illustration annulus - Image 2

noun

A ring- or donut-shaped area or structure.

Examples :

"The dartboard featured a red annulus worth double points. "

area part structure anatomy medicine biology

Illustration annulus - Image 1

noun

The region in a plane between two concentric circles of different radii.

Examples :

"The target around the bullseye had an annulus of blue paint. "

Illustration annulus - Image 1

noun

Any topological space homeomorphic to the region in a plane between two concentric circles of different radius.

Examples :

"The donut's shape, with its central hole, is an example of an annulus. "

Illustration annulus - Image 1

noun

The ring of the sun not covered by the moon in an annular solar eclipse.

Examples :

"During the annular solar eclipse, a bright annulus of sunlight remained visible around the dark moon. "

astronomy space science

Illustration annulus - Image 1

noun

Structure in a fern that consists of differentially thick-walled cells on a sporangium that bend and distort as a result of drying.

Examples :

"The science student observed how the annulus on the fern's sporangium dried and snapped back, scattering spores into the air. "

biology plant structure part

Illustration annulus - Image 1

noun

The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.

Examples :

"The young mushroom had a prominent annulus, a delicate ring around its stem, showing where the cap had once been connected. "

organism plant biology part

Illustration annulus - Image 1

noun

(oil and gas production) The space contained between the centre well bore and any external tubing. Sometimes used for separated gas flow.

Examples :

"During the well test, engineers monitored the pressure in the annulus to ensure no gas was leaking from the production tubing. "

technical industry energy