Quote Originally Posted by Eldan View Post
How about Null World? I think that has a ring to it.
Seconding this one, or maybe "Null System", since there is no "world" present, but there is a system orbiting the Null.

I'll also put forth my own slightly more arcane idea for nomenclature: call the moon or whatever that orbits nothing an "epicyclical world". The Epicycle was a concept in Ptolamaic astronomy where the orbits of planets were postulated to have circles within circles, epicycles, to explain retrograde motion in a geocentric cosmological model. Epicycles don't make sense from a gravitational standpoint, but neither does Spelljammer, and they perfectly describe the kind of planetary motion you are describing, where a heavenly body orbits a geometric point without any massive object being there. Bonus that the terminology comes from ancient astronomy, which sort of fits with D&D's largely pseudo-historical setting.