The official scientific definition of a Dimension is an axis of movement, such as height, length, and width.
For example, a point is 0-dimensional, a line is 1-dimensional, a plane is 2-dimensional, a cube is 3-dimensional, etc.
Time is generally considered to be the fourth dimension.
According to M-theory our multiverse is composed of 11 dimensions. According to Bosonic string theory there are 26 of them. And there are an infinite amount of dimensions within a Hilbert space.
Within this wiki it is not acceptable, and considered confusing, to use the term for anything other than spatial and temporal dimensions.
This includes inappropriately using it for universes, pocket universes, realms, worlds, or realities, etcetera.
Unfortunately, it is common within fiction, particularly North American superhero comicbooks, to misuse the term in such contexts.