Yes, there are some good definitions here.
I would say it’s fiction from a Catholic worldview. Basically, it’s not just a materialistic view, but there are forces at play both for good and evil, many of which are beyond our understanding. But we can get glimpses of them, and they make for much more interesting reading than the usual non-Christian worldview.
A Catholic worldview, in my opinion, is also richer than even the Protestant view. The universe is full of angels, demons, saints, and who knows what else. They are separated from us by a very thin glass window; they can see us but we can’t usually sense them.
Or not. But that’s my thought.