# What are 3D objects called?

The first thing I did was Google this, nothing. I know that 0D objects are points, 1D objects, lines, 2d objects, Planes, but when we reach 3D representations of 2D planes, like a square to a cube, we just start naming the shapes of 2D counterparts, which is good, but this is the only thing that's returned via the web, but we don't seem to classify it as anything other than a '3D object'. So, a square is a 2D object, so is a triangle, a circle, etc, but it's nice just to refer to them as planes.

So what is a 3D object called, other than just that?

• Squares, triangles, and circles aren't "planes". Commented Jan 6, 2016 at 20:08
• @littleO: Well, squares, triangles, and circles may not be "planes", but they are "plane figures".
– Blue
Commented Jan 6, 2016 at 20:11
• Ahhh thanks Bluey, I have no idea how I skipped a whole dimension. By the way, i've always wondered way a point is 0D, when it takes 1 point to represent the locality of a erm... a point :D So I mixed that mentality with how dimensions are defined via the general norm. Anyway, I derail, thanks for pointing that mistake out :) Commented Jan 6, 2016 at 20:42

## 2 Answers

Certain 3D objects ---cubes, spheres, cones--- are sometimes referred to as "solids", so that the study of them is "solid geometry" to distinguish from "plane geometry".

Polytope is a good word for what you are describing, I think.

The advantage of this term is that it can be extended to n dimensions.

A polygon (a plane figure) is termed a 2-polytope, a polyhedron (a solid figure) is termed a 3-polytope, and the higher dimensional analogues are called n-polytopes where n is the number of the dimension.

• This is potentially relevant, but it doesn't quite cover everything the OP mentioned: circles, for instance, are not polytopes Commented Jan 7, 2016 at 4:30