The noun warrant has 4 senses (first 1 from tagged texts)
1. (2) warrant -- (a writ from a court commanding police to perform specified acts)
2. warrant, stock warrant, stock-purchase warrant -- (a type of security issued by a corporation (usually together with a bond or preferred stock) that gives the holder the right to purchase a certain amount of common stock at a stated price; "as a sweetener they offered warrants along with the fixed-income securities")
3. sanction, countenance, endorsement, indorsement, warrant, imprimatur -- (formal and explicit approval; "a Democrat usually gets the union's endorsement")
4. guarantee, warrant, warrantee, warranty -- (a written assurance that some product or service will be provided or will meet certain specifications)
Overview of verb warrant
The verb warrant has 2 senses (first 1 from tagged texts)
1. (12) justify, warrant -- (show to be reasonable or provide adequate ground for; "The emergency does not warrant all of us buying guns"; "The end justifies the means")
2. guarantee, warrant -- (stand behind and guarantee the quality, accuracy, or condition of; "The dealer warrants all the cars he sells"; "I warrant this information")