audience has 3 distinct synonyms spread across 2 of its 4 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.
a gathering of spectators or listeners at a (usually public) performance
“the audience applauded”
the part of the general public interested in a source of information or entertainment
“every artist needs an audience”
an opportunity to state your case and be heard
“they condemned him without a hearing”
a conference (usually with someone important)
“he had a consultation with the judge”
Synonyms, antonyms and the broader and narrower relations for audience come from Princeton University’s WordNet. Full sources and licences.