A ring- or donut-shaped area or structure.
The ring of the sun not covered by the moon in an annular solar eclipse.
Structure in a fern that consists of differentially thick-walled cells on a sporangium that bend and distort as a result of drying.
The region in a plane between two concentric circles of different radii.
The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.
The space contained between the centre well bore and any external tubing. Sometimes used for separated gas flow.
Any topological space homeomorphic to the region in a plane between two concentric circles of different radius.
a circular annulus ring, frequently luminous, often golden, floating above the head
The metaphorical aura of glory, veneration or sentiment which surrounds an idealized entity.
A circular brace used to keep the head and neck in position.
nimbus, a luminous disc, often of gold, around or over the heads of saints, etc., in religious paintings.
The bias caused by the halo effect.
A cloud of gas and other matter surrounding and captured by the gravitational field of a large diffuse astronomical object, such as a galaxy or cluster of galaxies.
A rollbar placed in front of the driver, used to protect the cockpit of an open cockpit racecar.
A circular band of coloured light, visible around the sun or moon etc., caused by reflection and refraction of light by ice crystals in the atmosphere.
Anything resembling this band, such as an effect caused by imperfect developing of photographs.
To encircle with a halo.