dump has 14 distinct synonyms spread across 6 of its 10 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.
throw away as refuse
“No dumping in these woods!”
sever all ties with, usually unceremoniously or irresponsibly
“The company dumped him after many years of service”
drop (stuff) in a heap or mass
“The truck dumped the garbage in the street”
a piece of land where waste materials are dumped
Synonyms, antonyms and the broader and narrower relations for dump come from Princeton University’s WordNet. Full sources and licences.
a place where supplies can be stored
“an ammunition dump”