oversimplification has 1 distinct synonym spread across 2 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.
an act of excessive simplification; the act of making something seem simpler than it really is
a simplification that goes too far (to the point of misrepresentation)
Synonyms, antonyms and the broader and narrower relations for oversimplification come from Princeton University’s WordNet. Full sources and licences.
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.