cylindroid

At the most general level, a cylindroid is simply a cylinder that has been deformed in an intentional and well-defined way. The barrel die used in certain board role-playing games are sometimes described as being cylindroids in shape.

Most mathematical dictionaries that define the term at all say nothing more than “a cylinder with an elliptical cross-section.” (see for example the Harper-Collins Dictionary of Mathematics and the Oxford Concise Dictionary of Mathematics.) The term is also used for certain conoids, such as Plücker’s conoid.

The term is usually not included in general pocket dictionaries. The Random House Unabridged Dictionary defines cylindroid the noun as “a solid having the form of a cylinder, esp[ecially] one with an elliptical, as opposed to a circular, cross section,” and the adjective as “resembling a cylinder.”