warrant

Concise Oxford English Dictionary © 2008 Oxford University Press:
warrant/ˈwɒrənt/

▶noun

• 1 an official authorization enabling the police or some other body to make an arrest, search premises, etc.

• 2 a document entitling the holder to receive goods, money, or services.

• 3 Finance a negotiable security allowing the holder to buy shares at a specified price at or before some future date.

• 4 justification or authority.

• 5 an official certificate of appointment issued to an officer of lower rank than a commissioned officer.

▶verb

• 1 justify or necessitate.

• 2 officially affirm or guarantee.

– phrases
I (or I'll) warrant (you) dated no doubt.

– derivatives
warrantable adjective,
warrantableness noun,
warrantably adverb,
warranter noun.

– origin ME (in the senses ‘protector, safeguard’, and ‘protect from danger’): from vars of OFr. guarant (n.), guarantir (v.), of Gmc origin; cf. guarantee.