slum has 1 distinct synonym spread across 1 of its 2 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 district of a city marked by poverty and inferior living conditions
spend time at a lower socio-economic level than one's own, motivated by curiosity or desire for adventure; usage considered condescending and insensitive
“attending a motion picture show by the upper class was considered sluming in the early 20th century”
Synonyms, antonyms and the broader and narrower relations for slum come from Princeton University’s WordNet. Full sources and licences.