The warp
The parallel dimension a starship crosses to travel faster than light, and the place the Chaos gods and their daemons live.
also known as: the warp · warpen
Everything strange in this setting traces back to it. It is how ships cross the galaxy, it is where psychic power comes from, and it is where the Chaos gods are. It is also unstable: a storm in the warp can cut a region of space off for centuries, and something that lives there can reach through and rebuild a body on the other side. Magnus the Red calls it the Great Ocean, which is a kinder name than it deserves.