From The Art and Popular Culture Encyclopedia
The term slipstream was coined by cyberpunk author Bruce Sterling in an article originally published in SF Eye #5, July 1989. He wrote: "...this is a kind of writing which simply makes you feel very strange; the way that living in the twentieth century makes you feel, if you are a person of a certain sensibility." Slipstream fiction has consequently been referred to as "the fiction of strangeness," which is as clear a definition as any others in wide use. Science fiction authors James Patrick Kelly and John Kessel, editors of Feeling Very Strange: The Slipstream Anthology, argue that cognitive dissonance is at the heart of slipstream, and that it is not so much a genre as a literary effect, like horror or comedy.
Slipstream falls between speculative fiction and mainstream fiction. While some slipstream novels employ elements of science fiction or fantasy, not all do. The common unifying factor of these pieces of literature is some degree of the surreal, the not-entirely-real, or the markedly anti-real.