Marital separation, when a married couple ceases living together without a divorce
Legal separation, a legal status where married couples may disentangle their finances without divorce
Nonconformity to the world (separation from the world), a belief among some Protestant religious groups that the members of a church should be separate from "the world"
Political separation (separatism), advocacy of a state of cultural, ethnic, tribal, religious, racial, governmental or gender separation from the larger group
Separation of church and state, the idea that religion and government functions should be separate
Separation (aeronautics), rules to minimise the risk of collision between aircraft in flight
Separation (United States military), the process by which a service member leaves active duty
Separation anxiety disorder, an anxiety disorder in which an individual experiences excessive anxiety regarding separation from home and/or from people to whom the individual has a strong emotional attachment
Racial separation, the separation of different racial groups in daily life
Six degrees of separation, the idea that everyone is on average approximately six steps away, by way of introduction, from any other person on earth
Curdling of an emulsion in cookery is called "separation"
Cow-calf separation, practice of separating calves and mothers in the dairy industry