torus
noun
to·rus ˈtȯr-əs 
plural tori ˈtȯr-ˌī
-ˌē
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)
Example Sentences
Recent Examples on the Web These two time dimensions can be traced on to the surface of a torus. 
Zeeya Merali, Scientific American, 26 July 2022 The torus form and off-center void give a feeling of perpetual motion. Nicola Chilton, CNN, 20 June 2022 The surface of a sphere and the surface of a torus, for instance, are both two-dimensional manifolds. Quanta Magazine, 23 Mar. 2022 For example, the position and momentum of a swinging pendulum can each be represented as a point on a circle, so the phase space of a pendulum is two crossed circles, which together form a torus, or the surface of a doughnut. Quanta Magazine, 9 Dec. 2021 Surprisingly, the space of two-note chords is a Möbius strip, and the space of three-note chords is a kind of twisted triangular torus. George Hart, Scientific American, 14 Aug. 2013 To see why the local curvature of an arbitrary shape is almost never equal to its average curvature, consider a torus. Spyridon Michalakis, Scientific American, 1 Aug. 2020 Gauss-Bonnet implies that the average curvature of a torus, and of any shape with a single hole in it, is zero. Spyridon Michalakis, Scientific American, 1 Aug. 2020 As Io sweeps by Jupiter, the planet drags particles off its surface, forming a small magnetosphere, or plasma torus around the moon. Jennifer Leman, Popular Mechanics, 7 Apr. 2020 See More
Zeeya Merali, Scientific American, 26 July 2022 The torus form and off-center void give a feeling of perpetual motion. Nicola Chilton, CNN, 20 June 2022 The surface of a sphere and the surface of a torus, for instance, are both two-dimensional manifolds. Quanta Magazine, 23 Mar. 2022 For example, the position and momentum of a swinging pendulum can each be represented as a point on a circle, so the phase space of a pendulum is two crossed circles, which together form a torus, or the surface of a doughnut. Quanta Magazine, 9 Dec. 2021 Surprisingly, the space of two-note chords is a Möbius strip, and the space of three-note chords is a kind of twisted triangular torus. George Hart, Scientific American, 14 Aug. 2013 To see why the local curvature of an arbitrary shape is almost never equal to its average curvature, consider a torus. Spyridon Michalakis, Scientific American, 1 Aug. 2020 Gauss-Bonnet implies that the average curvature of a torus, and of any shape with a single hole in it, is zero. Spyridon Michalakis, Scientific American, 1 Aug. 2020 As Io sweeps by Jupiter, the planet drags particles off its surface, forming a small magnetosphere, or plasma torus around the moon. Jennifer Leman, Popular Mechanics, 7 Apr. 2020 See More Word History
Etymology
New Latin, from Latin, protuberance, bulge, torus molding
First Known Use
1563, in the meaning defined at sense 1
Medical Definition
torus
noun
to·rus ˈtōr-əs, ˈtȯr-
plural tori ˈtō(ə)r-ˌī ˈtȯ(ə)r-
ˈtȯ(ə)r- -ˌē
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