WordNet records no synonym and no antonym for saturn. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
a giant planet that is surrounded by three planar concentric rings of ice particles; the 6th planet from the sun
(Roman mythology) god of agriculture and vegetation; counterpart of Greek Cronus
“Saturday is Saturn's Day”
Synonyms, antonyms and the broader and narrower relations for saturn come from Princeton University’s WordNet. Full sources and licences.