What does "deep space" mean?

All of space beyond the gravitational influence of Earth, or outside the Solar System, or distant from stars.

What is a synonym for "deep space"?

Common synonyms include: bottomless pit, bowels, clearance, compass, divergence, extent.

adj, noun

adj, noun ·Rare ·Advanced level

Noun

1
All of space beyond the gravitational influence of Earth, or outside the Solar System, or distant from stars. uncountable
"Part of the time he spent in the speedster dashing hither and yon. Most of it, however, he spent in the vastly more comfortable mauler; to the armored side of which his tiny vessel clung with magnetic clamps while he slept and ate, gossiped and read, exercised and played with the mauler's officers and crew, in deep-space comradery."
2
any region in space outside the solar system wordnet

Adjective

1
Of or in the area of space beyond the gravitational influence of Earth, or outside the Solar System. not-comparable
"Bradley swore a mighty deep-space oath and braced himself against certain annihilation."

"Bradley swore a mighty deep-space oath and braced himself against certain annihilation."

Coined by American science fiction author E. E. Smith in 1934 in his novel Triplanetary, first serialized in Amazing Stories. After deep sea.