1. To attend an academic class or seminar informally without receiving academic credit for it: Carol wanted to audit a German class and learn some of the language, but she was not interested in getting any recognition of her achievement.
2. To examine and correct an official financial report; inspect: Mr. Smart was asked to audit, or to inspect, the accounts of the treasurer.
3. To scrutinize and evaluate something thoroughly: Mr. Goodman was an auditor and was appointed to audit and verify the correctness of the accounts regarding the property of the firm.