noun

1. a formal, often periodic examination and checking of accounts or financial records to verify their correctness
2. a settlement or adjustment of accounts
3. an account thus examined and adjusted
4. a final statement of account by auditors
5. any thorough examination and evaluation of a problem

Etymology: ME < L auditus, a hearing, pp. of audire: see audience

transitive verb, intransitive verb

1. to examine and check (accounts, claims, etc.)
2. to attend (a college course) simply to hear the lectures without receiving credit