sophisticate has 7 distinct synonyms spread across 3 of its 5 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.
make less natural or innocent
“Their manners had sophisticated the young girls”
practice sophistry; change the meaning of or be vague about in order to mislead or deceive
“Don't twist my words”
make more complex or refined
“a sophisticated design”
Synonyms, antonyms and the broader and narrower relations for sophisticate come from Princeton University’s WordNet. Full sources and licences.