warrant

noun

1. authorization, sanction, or justification.
2. something that serves to give reliable or formal assurance of something; guarantee, pledge, or security.
3. something considered as having the force of a guarantee or as being positive assurance of a thing: The cavalry and artillery were considered sure warrants of success.
4. a writing or document certifying or authorizing something, as a receipt, license, or commission.
5. Law. an instrument, issued by a magistrate, authorizing an officer to make an arrest, seize property, make a search, or carry a judgment into execution.
6. the certificate of authority or appointment issued to an officer of the armed forces below the rank of a commissioned officer.
7. a warehouse receipt.
8. a written authorization for the payment or receipt of money: a treasury warrant.