convulse has 7 distinct synonyms spread across 1 of its 6 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 someone convulse with laughter
“The comedian convulsed the crowd”
move or stir about violently
“The feverish patient thrashed around in his bed”
shake uncontrollably
“earthquakes convulsed the countryside”
cause to contract
“The spasm convulses her facial muscles”
contract involuntarily, as in a spasm
“The muscles in her face convulsed”
Synonyms, antonyms and the broader and narrower relations for convulse come from Princeton University’s WordNet. Full sources and licences.