From Pluralpedia, the collaborative plurality dictionary
caelesteplex (n.)
Applies tosystems, headspaces
CoinerCoined by Peter Parker of the Turtles All The Way Down sidesystem, Edward "Edwie" Nygma of the Voltaile Lovers Order sidesystem, Gamma Flare of the Dozakh Befallen sidesystem, Celete of an unknown sidesystem, The Lady of the Ultramundane Demiurge Galaxy sidesystem, and The Sir of the Ultramundane Demiurge Galaxy sidesystem, all of The Halcyonic Storms of Anemoia astropoly polyplex

A caelesteplex is a system that is so large and/or complex as to have multiple planets for their headmates to reside in. These systems can have different numbers of planets within their headspace and any number of solar systems or even galaxies. Although uncommon, it is possible for systems to even be part of the multiverse, to have voids within headspace, etc. and these all similarly fall under the caelesteplex definition. Any headspace that has anything beyond their planet's atmosphere (if they even have a full-on planet) can be known as or referred to as caelesteplex.

The word "caeleste/caelestum" comes from Latin for "heavenly; celestial; or heavenly bodies." The term uses the -plex suffix.