What term describes the region in space from one solar system to another?

The term that describes the region in space from one solar system to another is interstellar space. This region is located between the stars in a galaxy and encompasses the vast distances that separate solar systems. Interstellar space is characterized by a near-vacuum environment where the density of matter is extremely low compared to that within solar systems, such as our own.

In contrast, cislunar space refers to the region between the Earth and the Moon, which is still within the gravitational influence of both bodies rather than between stars. Galactic space generally refers to the broader regions of a galaxy, which encompasses numerous solar systems, but does not specifically indicate the area between individual solar systems. Interplanetary space, meanwhile, describes the space within a solar system, particularly the regions between planets, rather than the emptiness that exists between separate solar systems. Thus, interstellar space is the most accurate term to describe the vast expanse that separates solar systems.