Expanse

An expanse is a region of space that is widely spread out over many light years.

In 2401, expanse was listed as one of the results in Raffaela Musiker's search for the "red lady". (PIC: "The Next Generation")

Expanses

The term expanse is listed with other terms (such as planets, stars, wormholes, etc.) that have been identified as celestial objects, implying that expanses are recognized by Federation science as celestial objects.