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)

Examples of torus in a Sentence

Recent Examples on the Web

It's surrounded by what's called an accretion disk, which is a torus of hot gas swirling around the black hole, waiting to be consumed. —Keith Cooper, Space.com, 9 May 2025

So the ordinary torus has a Kervaire invariant of zero, while the twisted torus has a Kervaire invariant of 1. —Erica Klarreich, Quanta Magazine, 5 May 2025

There may be two companion stars that are interacting and sculpting the nebula, which is pinched in the middle by a fragmented ring or torus—looking like a half-eaten donut. —Alan Taylor, The Atlantic, 28 Apr. 2025

And since opposite sides of the box are identical — remember, the box is our 3D torus stand-in — those two circles will be identical as well. —Steve Nadis, Quanta Magazine, 27 Jan. 2025

Word History

Etymology

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

First Known Use

1563, in the meaning defined at sense 1

Rhymes for torus

• chloris
• chorus
• horus
• lores
• morrice
• morus
• orris
• porous
• porus
• authorise
• clitoris
• liquorice

Medical Definition

torus

noun

to·​rus ˈtōr-əs, ˈtȯr- 

plural tori ˈtō(ə)r-ˌī  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