# What do you call a cylinder with a hole down the center?

Imagine a 3D cylinder, like a can. Now imagine that almost like an axle spot for a wheel, there's a hole shaped in a perfect circle going down the cylinder. That's the shape I have to figure out the name for. Mathematical names are preferred, but any name works!

• There's only 1D in cylinder. – Jim Reynolds Feb 24 '15 at 21:46
• I think you call it a "pipe". (Well, actually, "cylinder" is the common term, unless it's exceptionally long.) – Hot Licks Feb 24 '15 at 22:24
• So you mean basically like a very tall doughnut? – Janus Bahs Jacquet Feb 24 '15 at 22:37
• Tube. Thick-wall or thin-wall. If cylinder is short enough, the holed variety might be called a washer. – Wayfaring Stranger Feb 25 '15 at 0:27
• A man, a worm, and a straw are topolgically equivalent. – tchrist Feb 25 '15 at 4:12

A solid cylinder with an axial hole is still a cylinder. If the length of the cylinder is very much less than the diameter and the bore is small compared to the diameter it is a washer. If the length is much larger than the diameter, and especially if the bore is nearly as large as the cylinder diameter it is a tube.

• I think "washer" is only likely to be properly recognized in mechanical contexts, and may be especially misleading or inappropriate for some others. – Iszi Feb 24 '15 at 23:13
• "washer" is used in mathematical contexts for integration of certain types of functions. – Random832 Feb 25 '15 at 3:38
• True: I might say "like a washer" rather than describing it as a washer. – JDługosz Feb 25 '15 at 5:41
• A cylinder with `length < diameter` is still a cylinder. – Gusdor Feb 25 '15 at 9:55
• Yes,but if length << diameter it's also a washer. – WhatRoughBeast Feb 25 '15 at 20:26

Cylinder -Wiki

Open Cylinder

A cylinder -with the generating lines perpendicular to the bases, with its ends closed to form two circular surfaces- with a hole perpendicular to its base, is a right circular, open cylinder.
Its function tells us if it's a pipe, washer, bearing, beer can, ect.

Google's 4th picture hit for open cylinder:

Colloquially, i'd just call it a hollow cylinder.

• Not just colloquially. Whenever this shape appears in physics, it's called a hollow cylinder. – Martin Krzywinski Feb 24 '15 at 23:32
• If I read the phrase "hollow cylinder", I'd be wondering if it had end-caps or not. – David Richerby Feb 25 '15 at 18:20
• â€¦ not to be confused with a foolish Dutchman. – J. C. Salomon Feb 25 '15 at 22:35

In technical terms, it seems that the three dimensional object would be called an annular cylinder:

A problem in generalized thermoelasticity for an infinitely long annular cylinder

Annulus is certainly a two-dimensional object in geometry describing one cross section of an open cylinder:

NOUN

technical

1 A ring-shaped object, structure, or region.

A barrel is also a common less technical reference for a bored cylinder:

A cylindrical tube forming part of an object such as a gun or a pen:

Tube, pipe and ring also offer less technical descriptions.

International Journal of Engineering Science Volume 26, Issue 3, 1988, Pages 301â€“306

www.oxforddictionaries.com

en.wikipedia.org

• Annulus appears to be 2D... – anemone Feb 24 '15 at 22:01
• Though mathematically similar, an annulus is considered very flat (like a washer) or even 2D. Much of any depth to it and people wouldn't call it an annulus anymore. I don't have a good single word for what is desired but a 'cylinder with bored/rifled center'. – Mitch Feb 24 '15 at 22:01
• As the other comments mention, an annulus is 2-dimensional; this object is an annular cylinder. – Nick Matteo Feb 25 '15 at 1:55
• I recall encountering some writing by a non-native speaker that used annulus. That's unheard of in American English and I suggested ring for that particular use. – JDługosz Feb 25 '15 at 5:39
• @jdlugosz: In technical mathematical writing, annulus is the recognized term for the 2-dimensional shape, partly because ring is used in mathematics for something completely different. – Nate Eldredge Feb 25 '15 at 6:08

I've always considered that a Toroid

http://en.wikipedia.org/wiki/Toroid

• "toroid" is a bit too vague. It is like calling a square a quadrilateral. – Umberto P. Feb 25 '15 at 20:59
• You can call it a "rectangular toroid" to specify the shape of its cross section. – Muqo Feb 26 '15 at 15:34

Stealing from other answers as well.

• Tube (if it's longer than it is wide)
• Tunnel (if it's a tube big enough to crawl or drive through)
• Pipe (if it's long and fixed in place)
• Hose or Conduit (if it bends)
• Ring or Disc or Washer (if it's shorter than it is wide)
• Straw (if you drink through it)
• Bucket (if it has a cover on one end)
• Bottle (if it's a bucket with the open end narrower than the closed end)
• Can or Canister or Capsule (if it has a cover on both ends)
• Duct (if it has junctions)
• Barrel (if you shoot projectiles through it, or it's made of compressed wood planks, or it's a canister big enough to store a person)
• Toroid (if its ends meet)
• Sleeve (if it's designed to snugly surround something)
• Coil or Solenoid (if it's made by tightly winding material around a cylinder)
• Bushing (if it has internal, inverse screw threading)

In the UK Steel Industry it is referred to as a Hollow Bar

In French, it would be called "un manchon". I found the following translations for this word: muff, sleave, bush(ing), socket. I don't know which one is the most appropriate.

• Tube
• Ring
• Pipe
• Washer
• Straw
• Hollow cylinder
• Cylindrical shell
• Bored cylinder

Or, perhaps the most technical name for it:

• Long round thing with a hole through it

This is what I remember using in geometry class: "coaxial cylinders". Pipe is correct too. Disclaiming that the hole is not implied there. This question is very close to yours, check it out.

It's called a tube - a hollow cylinder. E.g.; gun barrels are sometimes called metal tubes; plastic sewer pipes get addressed as tubes; and architects get the privilege to call tunnels tube-shaped structures.