to·​rus | \ ˈtȯr-əs How to pronounce torus (audio) \
plural tori\ ˈtȯr-​ˌī How to pronounce tori (audio) , -​ˌē \

Definition of torus

1 : a large molding of convex profile commonly occurring as the lowest molding in the base of a column
2 : the thickening of a membrane closing a wood-cell pit (as of gymnosperm tracheids) having the secondary cell wall arched over the pit cavity
3 : a doughnut-shaped surface generated by a circle rotated about an axis in its plane that does not intersect the circle broadly : toroid
4 : a smooth rounded anatomical protuberance (such as a bony ridge on the skull)

Examples of torus in a Sentence

Recent Examples on the Web

The Euler characteristic of a sphere is 2; that of a torus is 0. Quanta Magazine, "A Proof That Some Spaces Can’t Be Cut," 13 Jan. 2015 The joint European torus (JET), a tokamak hosted in the United Kingdom that produced its first plasma in 1983 and is the most powerful fusion facility in use, is also providing an important testbed for materials and technologies for ITER. Giulia Pacchioni, Scientific American, "The Road to Fusion," 26 Aug. 2019 That’s important because the glowing accretion disk sends visible light toward the dark torus, where it is absorbed and re-emitted as infrared light. Quanta Magazine, "Galactic Beacons Get Snuffed Out in a Cosmic Eyeblink," 21 Nov. 2018 Because of this, any change in the accretion disk will later be echoed within the torus. Quanta Magazine, "Galactic Beacons Get Snuffed Out in a Cosmic Eyeblink," 21 Nov. 2018 The stellarator, however, traps the plasma in a twisting and spiraling shape, rather than the torus (doughnut shape) of a tokamak. Jay Bennett, Popular Mechanics, "German Nuclear Fusion Experiment Sets Records for Stellarator Reactor," 26 June 2018 An animation of the central torus of gas and dust, thought to surround the supermassive black hole of an active galaxy. Amina Khan,, "After years of searching, scientists finally trace high-energy neutrinos to a distant blazar," 12 July 2018 At least once, according to JET's operators, these speakers helped them track down a loose clamp in the torus's immense and complicated structure. Eric Limer, Popular Mechanics, "Why Any Good Fusion Reactor Needs a Decent Set of Speakers," 26 Apr. 2016 Then a series of prints and embroideries play with using scribbles to mark points on a grid—either flat, or applied to mathematical shapes like a torus or sphere. Jonathan Evans, Esquire, "This Brand Wants You to Rethink Your Everyday Clothes," 6 Feb. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'torus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of torus

1563, in the meaning defined at sense 1

History and Etymology for torus

New Latin, from Latin, protuberance, bulge, torus molding

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More Definitions for torus


to·​rus | \ ˈtōr-əs, ˈtȯr- How to pronounce torus (audio) \
plural tori\ ˈtō(ə)r-​ˌī How to pronounce tori (audio) , ˈtȯ(ə)r-​ How to pronounce tori (audio) , -​ˌē \

Medical Definition of torus

1 : a doughnut-shaped surface generated by a circle rotated about an axis in its plane that does not intersect the circle
2 : a smooth rounded anatomical protuberance (as a bony ridge on the skull) a supraorbital torus

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