A place (or notional place) that exists as an ordinary part of a society but which is also in some way demarcated, separate, or marginal, meaning the norms of wider society (though present) can become blurred, undermined, resisted, or transformed by different modes of thought and behaviour arising within the place itself.
The concept was first used by the French philosopher, Michel Foucault, in contrast to the idea of utopia as an ideal or unreal space, with examples including prisons, fairgrounds, theatres, and brothels. Later use in cultural theory and the social sciences has seen the idea interpreted expansively to include, e.g., whole cities, internet sites, and fictional worlds.
1970s. From hetero- + -topia, after French hétérotopie (M. Foucault, 1966 or earlier).