Subspace.  Slipspace.  Hyperspace.  Speculative science fiction gave us many names, and picking one was not easy.  The science fiction fans had vested interests in getting the name “their” universe used accepted, and the “debate” was energetic.  Submariners picked subspace, and it gained early acceptance.  Hyperspace was most popular when the US Navy began to expand, and the new sailors used it to annoy the submariners.  God bless inter-service rivalry.