Subspace

In mathematics, if a set with certain properties is called a space, then a subset of which with same properties is usually called a subspace. Those with entries in Wikipedia are:
- Linear subspaces (also called vector subspaces) in linear algebra;
- Topological subspaces in topology.
There is a fictional notion of subspace used in science fiction; see Hyperspace.
The psychological state of the submissive partner in a BDSM scene is sometimes described as "subspace" or "sub space": see subspace (BDSM)