to·​rus ˈtȯr-əs How to pronounce torus (audio)
plural tori ˈtȯr-ˌī How to pronounce torus (audio)
: a large molding of convex profile commonly occurring as the lowest molding in the base of a column
: the thickening of a membrane closing a wood-cell pit (as of gymnosperm tracheids) having the secondary cell wall arched over the pit cavity
: a doughnut-shaped surface generated by a circle rotated about an axis in its plane that does not intersect the circle
broadly : toroid
: a smooth rounded anatomical protuberance (such as a bony ridge on the skull)

Examples of torus in a Sentence

Recent Examples on the Web Next, map the circle onto the two-dimensional surface of an inner tube (a one-holed torus). Kevin Hartnett, Quanta Magazine, 22 Aug. 2023 Consider the surface of a doughnut, or torus — a two-dimensional manifold. Jordana Cepelewicz, Quanta Magazine, 15 June 2023 The stator converts its thrust force and torque into longitudinal and meridian motions of the torus wheel, respectively, making the torus work as an omnidirectional wheel on a plane. IEEE Spectrum, 21 Aug. 2022 What’s more, some AGN have a dusty torus, the geometric equivalent of a donut, in the same plane as their accretion disk, but much, much bigger and thicker. Summer Ash, Discover Magazine, 16 July 2018 The torus itself spans only about 20 light-years, an extremely small region of space compared with the larger galaxy M77. Alison Klesman, Discover Magazine, 2 Mar. 2018 But the torus proved tricky. Nicola Chilton, CNN, 20 June 2022 However, the mastoid processes and large, and the back of the skull does not show the angulated occipital bone and strong transverse torus found in large H. heidelbergensis individuals. Julia Musto, Fox News, 26 June 2021 This instrument made observations of the torus in Cygnus A possible for the first time, Lopez-Rodriguez explained. Chelsea Gohd, Discover Magazine, 23 Oct. 2018 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'torus.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

First Known Use

1563, in the meaning defined at sense 1

Time Traveler
The first known use of torus was in 1563

Dictionary Entries Near torus

Cite this Entry

“Torus.” Dictionary, Merriam-Webster, Accessed 30 Sep. 2023.

Medical Definition


plural tori ˈtō(ə)r-ˌī How to pronounce torus (audio) ˈtȯ(ə)r- How to pronounce torus (audio)
: a doughnut-shaped surface generated by a circle rotated about an axis in its plane that does not intersect the circle
: a smooth rounded anatomical protuberance (as a bony ridge on the skull)
a supraorbital torus
Last Updated: - Updated example sentences
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