What is Auditor?

Legal Definition
An auditor is a person or a firm appointed by a company to execute an audit. To act as an auditor, a person should be certified by the regulatory authority of accounting and auditing or possess certain specified qualifications. Generally, to act as an external auditor of the company, a person should have a certificate of practice from the regulatory authority.
-- Wikipedia
Legal Definition
1. An official of a government agency whose job is to inspect and examine records of public m monies made by appointed authorities. 2. An appointee of the court.
Legal Definition
An officer whose duty is to examine the accounts of officers who have received and dishursed public moneys by lawful authority. See Acts of Congress, April 3, 1817; 3 Story's Laws U. S. 1630; and the Act of February 24, 1819, 3 Story's L. U. S. 1722.
-- Bouviers Law Dictionary
Legal Definition
Practice. Persons lawfully appointed to examine and digest accounts referred to them, take down the evidence in writing, which may be lawfully offered in relation to such accounts, and prepare materials on which a decree or judgment may be made; and to report the whole, together with their opinion, to the, court in which such accounts originated. 6 Cranch, 8; 1 Aik. 145; 12 Mass. 412.

2. Their report is not, per se, binding and conclusive, but will become so, unless excepted to. 5 Rawle, R. 323. It may be set aside, either with or without exceptions to it being filed. In the first case, when errors are apparent on its face, it may be set aside or corrected. 2 Cranch, 124; 5 Cranch, 313. In the second case, it may be set aside for any fraud, corruption, gross misconduct, or error. 6 Cranch, 8; 4 Cranch, 308; 1 Aik. 145. The auditors ought to be sworn, but this will be presumed. 8 Verm. 396.

3. Auditors are also persons appointed to examine the accounts subsisting between the parties in an action of account render, after a judgment quod computet. Bac. Ab. Accompt, F.

4. The auditors are required to state a special account, 4 Yeates, 514, and the whole is to be brought down to the time when they make an end of their account. 2 Burr. 1086. And auditors are to make proper charges and credits without regard to time, or the verdict. 2 S. & R. 317. When the facts or matters of law are disputed before them, they are to report them to the court, when the former will be decided by a jury, and the latter by the court, and the result sent to the auditors for their guidance. 5 Binn. 433.
-- Bouviers Law Dictionary
Legal Definition
A public officer whose function is to examine and pass upon the accounts and vouchers of officers who have received and expended public money by lawful authority. In practice. An officer (or officers) of the court, assigned to state the items of debit and credit between the parties in a suit where accounts are in question, and exhibit the balance. Whitwell v. Willard, 1 Meta (Mass.) 218. In English law. An officer or agent of the crown, or of a private individual, or corporation, who examines periodically the accounts of under officers, tenants, stewards, or bailiffs, and reports the state of their accounts to his principal.
See also
-- Black's Law Dictionary
Legal Definition
An examiner of accounts appointed by a court or otherwise.
-- Ballentine's Law Dictionary