warrant

anything that gives authority for an action or decision; authorization; sanction

a document that certifies or guarantees, such as a receipt for goods stored in a warehouse, a licence, or a commission

an authorization issued by a magistrate or other official allowing a constable or other officer to search or seize property, arrest a person, or perform some other specified act

(in certain armed services) the official authority for the appointment of warrant officers

a security that functions as a stock option by giving the owner the right to buy ordinary shares in a company at a specified date, often at a specified price

to guarantee the quality, condition, etc, of (something)

to give authority or power to

to attest to or assure the character, worthiness, etc, of

to guarantee (a purchaser of merchandise) against loss of, damage to, or misrepresentation concerning the merchandise

to guarantee (the title to an estate or other property)

to declare boldly and confidently