erupt has 19 distinct synonyms spread across 7 of its 8 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.
break out
“The tooth erupted and had to be extracted”
become active and spew forth lava and rocks
“Vesuvius erupts once in a while”
force out or release suddenly and often violently something pent up
“break into tears”
appear on the skin
“A rash erupted on her arms after she had touched the exotic plant”
Synonyms, antonyms and the broader and narrower relations for erupt come from Princeton University’s WordNet. Full sources and licences.