In mathematics

• Euclidean subspace
  Euclidean subspace
  In linear algebra, a Euclidean subspace is a set of vectors that is closed under addition and scalar multiplication. Geometrically, a subspace is a flat in n-dimensional Euclidean space that passes through the origin...
  
  , in linear algebra, a set of vectors in n-dimensional Euclidean space that is closed under addition and scalar multiplication
• Linear subspace
  Linear subspace
  The concept of a linear subspace is important in linear algebra and related fields of mathematics.A linear subspace is usually called simply a subspace when the context serves to distinguish it from other kinds of subspaces....
  
  , in linear algebra, a subset of a vector space that is closed under addition and scalar multiplication
• Affine subspace, linear manifold or linear variety, is a geometric structure that generalizes the affine properties of Euclidean space. It is a subset of a vector space closed under affine combinations of vectors in the space.
• Subspace topology
  Subspace topology
  In topology and related areas of mathematics, a subspace of a topological space X is a subset S of X which is equipped with a natural topology induced from that of X called the subspace topology .- Definition :Given a topological space and a subset S of X, the...
  
  , in topology and related areas of mathematics

In science fiction

• Hyperspace (science fiction)
  Hyperspace (science fiction)
  Hyperspace is a plot device sometimes used in science fiction. It is typically described as an alternative region of space co-existing with our own universe which may be entered using an energy field or other device...
  
  , a fictional parallel universe sometimes referred to as subspace
• Subspace (Star Trek)
  Subspace (Star Trek)
  In the Star Trek fictional universe, subspace is a feature of space-time which facilitates faster-than-light transit, in the form of interstellar travel or the transmission of information. Subspace obeys different laws of physics...
  
  , a medium for faster-than-light communications or travel

In games

• SubSpace (video game), a two-dimensional space shooter computer game
• The Subspace Emissary, the two player Adventure mode in the video game Super Smash Bros. Brawl.

Other uses

• Subspace (BDSM)
  Subspace (BDSM)
  Subspace , in the context of a BDSM scene, is a psychological state that can sometimes be entered by the person bottoming in the scene. The term is unrelated to the mathematical term subspace....
  
  , the psychological state of the submissive partner in a BDSM scene
• "Subspace" (song), a single by Funker Vogt