torus

American  

[tawr-uhs] / ˈtɔr əs /

noun

• tori
  plural

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.

---

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

---

torus Scientific  

/ tôr′əs /

• tori
  plural

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.

---

Other Word Forms

Noun Inflected Forms

• tori
  plural

Etymology

Origin of torus

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

Example Sentences

See Examples For:

torus tori

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

As with most active galaxies, NGC 4945's black hole and disk are shrouded by a dense cloud of dust called a torus, which blocks some of that light.

From Science Daily ● Jan. 12, 2024

Each year Dr. Morgenthaler has monitored volcanic activity through IoIO, he has noticed some kind of increased concentration, or brightening, of gases in the plasma torus.

From New York Times ● Jan. 25, 2023

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

From New York Times ● Jan. 25, 2023

The torus room, normally dry, was hazy with steam.

From "Meltdown" by Deirdre Langeland

First noted at a World Cup match 18 years ago in France, the practice is known as “Tatsu tori ato wo nigosazu” — a departing bird does not muddy the water.

From Los Angeles Times ● Jun. 22, 2026

To challenge the long-accepted idea, the researchers built two compact, self-contained surfaces shaped like doughnuts, known as tori.

From Science Daily ● Apr. 22, 2026

No sound is needed to scare off seabirds with a device called a tori line.

From Washington Post ● Aug. 17, 2022

Now we replace the torus with a chain of smaller tori sitting entirely within the first torus to get level 1 of the construction.

From Scientific American ● Jul. 8, 2018

In the Ionic buildings of Attica the base of the column consists of two tori separated by a trochilus.

From A History of Greek Art by Frank Bigelow Tarbell