thunder has 9 distinct synonyms spread across 4 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.
move fast, noisily, and heavily
“The bus thundered down the road”
be the case that thunder is being heard
“Whenever it thunders, my dog crawls under the bed”
to make or produce a loud noise
“The river thundered below”
a booming or crashing noise caused by air expanding along the path of a bolt of lightning
Synonyms, antonyms and the broader and narrower relations for thunder come from Princeton University’s WordNet. Full sources and licences.