torus

American  

[tawr-uhs] / ˈtɔr əs /

noun

plural

tori

1. Architecture. a large convex molding, more or less semicircular in profile, commonly forming the lowest molding of the base of a column, directly above the plinth, sometimes occurring as one of a pair separated by a scotia and fillets.

2. Geometry.

   1. Rarely a doughnut-shaped surface generated by the revolution of a conic section, especially a circle, about an exterior line lying in its plane.

   2. the solid enclosed by such a surface.

3. Botany.

   1. the receptacle of a flower.

   2. a thickening of the wall membrane in the bordered pits occurring in the tracheid cells of the wood of many conifers.

4. Anatomy. a rounded ridge; a protuberant part.

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torus British  

/ ˈtɔːrəs /

noun

1. Also called: tore.  a large convex moulding approximately semicircular in cross section, esp one used on the base of a classical column

2. geometry a ring-shaped surface generated by rotating a circle about a coplanar line that does not intersect the circle. Area: 4π² Rr ; volume: 2π² Rr ², where r is the radius of the circle and R is the distance from the line to the centre of the circle

3. botany another name for receptacle

4. anatomy a ridge, fold, or similar linear elevation

5. astronomy a dense ring of gas and dust which surrounds a dying star, containing most of the star's ejected gas

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torus Scientific  

/ tôr′əs /

plural

tori

1. A surface generated by rotating a circle about an axis that is in the same plane as the circle but does not intersect it. A torus resembles a donut and is a subtype of toroid.

2. The torus-shaped apparatus that contains plasma in nuclear fusion reactors.

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Etymology

Origin of torus

First recorded in 1555–65; from Latin: literally, “strand, thong, raised ridge”

Example Sentences

These plasma clumps are carried along by the star's magnetic field, forming a doughnut shaped structure called a torus.

From Science Daily • Mar. 27, 2026

A puffy donut-shaped cloud of material called a torus surrounds the accretion disk.

From Science Daily • May 8, 2024

Or it could mean that the torus was rapidly diffusing in response to the intense eruption.

From New York Times • Jan. 25, 2023

Studying the anomaly might draw out, in better detail, the different kinds of volcanoes on Io, as well as the interactions between the plasma torus and other massive moons around Jupiter.

From New York Times • Jan. 25, 2023

Steam that passes through the torus is scrubbed of most of its radioactive isotopes before it leaves the building, a vast improvement over allowing the steam to enter the environment without any intervention.

From "Meltdown" by Deirdre Langeland