A "fractal" is an object that is self-similar on different scales. A "fractal cosmos" therefore is a cosmos that encompasses universes and particles of different orders of magnitude.
Every universe in a fractal cosmos is inside a series of higher-order universes.
Likewise, every particle in a fractal cosmos is a wave that is superimposed upon a series of higher-order particles.
The fractal cosmos consists of many orders of fractal particles and many orders of fractal universes, which are all interconnected in one single fractal object of cosmological proportions.