A wormhole, in science fiction, is a speculative passage from one location in three-dimensional space to another. It is based on the concept that space has more than three dimensions, and that 3D space can be "folded" within 4D space much as a 2D piece of cloth can be folded within 3D space. The General Theory of Relativity says that wormholes may exist. This has not been proven so far. It is impossible to prove that no wormholes exists anywhere, and thus they fail the falsifiability requirement of science.
The significance of a wormhole is that it would allow a trip through it to take much less time than a journey between the same two points in conventional space. The mouths of a wormhole may be at any two points in spacetime, including at different times; this would allow time travel by going through the wormhole.
The first prediction of a wormhole was made by physicist Hermann Weyl in 1921, and physicist John Wheeler coined the term “wormhole” in 1957.