space has 7 distinct synonyms spread across 6 of its 10 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the unlimited expanse in which everything is located
“they tested his ability to locate objects in space”
an empty area (usually bounded in some way between things)
“the architect left space in front of the building”
an area reserved for some particular purpose
“the laboratory's floor space”
any location outside the Earth's atmosphere
“the astronauts walked in outer space without a tether”
the interval between two times
“the distance from birth to death”
a blank area
“write your name in the space provided”
one of the areas between or below or above the lines of a musical staff
“the spaces are the notes F-A-C-E”
(printing) a block of type without a raised letter; used for spacing between words or sentences
place at intervals
“Space the interviews so that you have some time between the different candidates”
Synonyms, antonyms and the broader and narrower relations for space come from Princeton University’s WordNet. Full sources and licences.