Separation may refer to several different subjects:
- Separation processes, in chemistry
- Flow separation, separation of a fluid boundary layer from the surface of a solid body moving relative to the fluid
- Legal separation, a legal status where married couples may disentangle their finances without divorce
- Separation (United States military), process by which a service member leaves active duty
- Separation mastering, in music recording
- Separation (Air Traffic Control),rules to minimise the risk of collision between aircraft in flight
- Separation of church and state, the idea that religion and government functions should be separate
- Separation axioms, concepts in the area of mathematics called topology
- Separated sets, related concept in topology, two sets disjoint from the other's closure
- Political separation - Separatism - as in those seeking to "separate" their group or territory from the larger entity
