This type of matter is special, as you can tell from the name. Repulsive matter, well, is repulsive. It repels every single type of matter, object, force, or anything in general. That also means gravity. Repulsive matter was the reason the Isolated Dimension got all of its Metareality Links cut from the main Metareality-Web. It is unknown when this matter first formed, all we know is that the Isolated Dimension is full of it. Read the 'property' section for more info.
Repulsive matter may also be referred to an entity known as Jonothon.