The physical realm includes seven compartments, or worlds. These are called, Eretz, Adamah, Gey, Neshiyah, Tziyah, Arka, Tevel. Our physical earth corresponds to Tevel. When Rabbi Yosi inquires as to the nature of the world called Tziyah, Rabbi Abba replies that this realm is the location of Hell.
The world of Neshiyah, the Zohar explains, is called oblivion. It is totally forgotten, for it is without any form.