audit has 4 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.
an inspection of the accounting procedures and records by a trained accountant or CPA
a methodical examination or review of a condition or situation
“he made an audit of all the plants on his property”
examine carefully for accuracy with the intent of verification
“audit accounts and tax returns”
attend academic courses without getting credit
Synonyms, antonyms and the broader and narrower relations for audit come from Princeton University’s WordNet. Full sources and licences.