Veil

A metaphysical barrier between the mortal realm and the Fade. Neither spirits nor mortal beings can easily pass physically through the veil, but the consciousness of mortal dreamers easily does so.

The veil is weakened in places where a lot of death has occurred and there is no known way to repair it.

The veil is not an object; it cannot be touched or seen. It is a metaphor used by mortal scholars to explain the interactions between the two different realities.