sputter has 13 distinct synonyms spread across 5 of its 7 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.
make an explosive sound
“sputtering engines”
cause to undergo a process in which atoms are removed
“The solar wind protons must sputter away the surface atoms of the dust”
the noise of something spattering or sputtering explosively
“he heard a spatter of gunfire”
Synonyms, antonyms and the broader and narrower relations for sputter come from Princeton University’s WordNet. Full sources and licences.