Noun

sci-fi (uncountable)

1. (colloquial) Short form of science fiction.

Science fiction is a genre of fiction dealing with the impact of imagined innovations in science or technology. It differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature (though some elements in a story might still be pure imaginative speculation). Exploring the consequences of such differences is the traditional purpose of science fiction, making it a "literature of ideas". Science fiction is largely based on writing rationally about alternative possibilities. The settings for science fiction are often contrary to known reality, but the majority of science fiction relies on a considerable degree of suspension of disbelief provided by potential scientific explanations to various fictional elements.

These may include:

• A setting in the future, in alternative timelines, or in an historical past that contradicts known facts of history or the archaeological record
• A setting in outer space, on other worlds, or involving aliens
• Stories that involve technology or scientific principles that contradict known laws of nature
• Stories that involve discovery or application of new scientific principles, such as time travel or psionics, or new technology, such as nanotechnology, faster-than-light travel or robots, or of new and different political or social systems (e.g., a dystopia, or a situation where organized society has collapsed)