Plane

In the terminology used in the Wongery (and by many pediologists), a plane is a continuous expanse of self-contained space, that is to say, that doesn't physically connect to any other such expanses. There's a little leeway given if the connections are very small; two large planes can be physically connected through a narrow wormhole and still be considered separate planes. This may seem to lead to ambiguity concerning where exactly the line is drawn, and just how big the connections can be between two planes before they have to be considered one, but in practice such borderline cases very seldom arise; for the most part, it's pretty clear what are and are not separate planes.

Generally, the unmodified word plane is reserved for relatively large expanses--hundreds of kilometers across, at the very least. Smaller self-contained spaces are called by other terms such as "pocket planes". Pediologists don't hold to this distinction, and technically any self-contained space can accurately be called a plane, but in common usage other terms are still used for particularly small planes.

There are other terms that are in common usage to refer to planes, as well. In many places, planes are often referred to as "dimensions", though this usage is frowned upon by pediologists, not least because of its possible confusion with the geometrical concept of a dimension. Of course, the word "plane" has its own geometrical meaning at variance with the pediological one, referring specifically to a flat two-dimensional expanse, whereas most planes in the pediological sense—or at least most known planes of interest to pediologists—are, or at least locally seem, three-dimensional. Because of this, some pediologists prefer to eschew the word "plane" as well, at least in technical contexts, and prefer more specific terms such as "chor" (pronounced like "core", which perhaps exacerbates the issue by having both a homograph and a homophone; from the Greek χωρος), "perioch" (from the Greek περιοχη), or "singulum" (plural singula; from Latin, and not to be confused with the homophonic "cingulum"). Such terms, however, have never caught on outside of scholarly contexts.

One example of a plane is Tamamna, the universe in which the Sun and the Earth are located. (In general, all universes are planes, but not all planes are universes.)