cascade has 2 distinct synonyms spread across 2 of its 5 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.
a small waterfall or series of small waterfalls
a succession of stages or operations or processes or units
“progressing in severity as though a cascade of genetic damage was occurring”
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Synonyms, antonyms and the broader and narrower relations for cascade come from Princeton University’s WordNet. Full sources and licences.