| Subject |
has dimension |
has definition |
|---|
| conic section | 2 | |
| fractal | fractional | A pattern that repeats itself or nearly repeats itself on many different scales of magnification. For example, suppose that some ink on a piece of paper appears to form a star. If you look at the piece of paper with a magnifying glass, you see that the dark areas are not solid black, but are formed of tiny stars themselves. If you look at one of these small stars with a microscope, you see that the dark areas of each of the tiny stars is formed from an arrangement of even tinier stars. Such a repeating pattern of stars would be called a fractal. |
| line | 1 | A geometrical object with one dimension |
| plane | 2 | |
| point | 0 | A geometrical object with zero dimensions, a location and possibly a time |
| sphere | 3 | The outer surface of a ball. The surface of a familiar three-dimensional ball has two dimensions (which can be labeled by two numbers such as "latitude" and "longitude," as on the surface of the earth). The concept of a sphere, though, applies more generally to balls and hence their surfaces, in any number of dimensions. A one-dimensional sphere is a fancy name for a circle; a zero-dimensional sphere is two points (as explained in the text). A three-dimensional sphere is harder to picture; it is the surface of a four-dimensional ball. |
| torus | 3 | The two-dimensional surface of a doughnut. |
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