parvenu has 4 distinct synonyms spread across 3 of its 3 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.
characteristic of someone who has risen economically or socially but lacks the social skills appropriate for this new position
of or characteristic of a parvenu
a person who has suddenly risen to a higher economic status but has not gained social acceptance of others in that class
Synonyms, antonyms and the broader and narrower relations for parvenu come from Princeton University’s WordNet. Full sources and licences.