Isodor
Different culture have their own names for the world but in the Common tongue the Prime Material Plane is called "Isodor."
Scholars and cosmologists disagree on the true nature of the world but schools of though consistently put the elemental chaos abyssal depths "below" the plane and the astral sea and outer planes "above" it--to whatever extent directionality makes sense in a cosmology that cannot be mapped.
Scholars and cosmologists disagree on the true nature of the world but schools of though consistently put the elemental chaos abyssal depths "below" the plane and the astral sea and outer planes "above" it--to whatever extent directionality makes sense in a cosmology that cannot be mapped.