come up has 23 distinct synonyms spread across 10 of its 12 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.
bring forth, usually something desirable
“The committee came up with some interesting recommendations”
be mentioned
“These names came up in the discussion”
gather (money or other resources) together over time
“She had scraped together enough money for college”
Synonyms, antonyms and the broader and narrower relations for come up come from Princeton University’s WordNet. Full sources and licences.