audit (n.) Look up audit at Dictionary.com
early 15c., "official examination of accounts," from Latin auditus "a hearing, a listening," past participle of audire "to hear" (see audience). Official examination of accounts originally was an oral procedure. Also formerly used in a sense "official audience, judicial hearing or examination" (1590s).
audit (v.) Look up audit at Dictionary.com
mid-15c., "examine and verify (accounts)," from audit (n.). Meaning "attend (a course, etc.) without intending to earn credit by doing course-work" is from 1933. Related: Audited; auditing.