warrant in WordNet English dictionary

1. formal and explicit approval
   "a Democrat usually gets the union's endorsement"
   sanction  countenance  endorsement  indorsement  warrant  imprimatur 
   
2. a written assurance that some product or service will be provided or will meet certain specifications
   guarantee  warrant  warrantee  warranty 
   
3. 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"
   warrant  stock warrant  stock-purchase warrant 
   
4. a writ from a court commanding police to perform specified acts
   warrant 
   

1. stand behind and guarantee the quality, accuracy, or condition of
   "The dealer warrants all the cars he sells"; "I warrant this information"
   guarantee  warrant 
   
2. show to be reasonable or provide adequate ground for
   "The emergency does not warrant all of us buying guns"; "The end justifies the means"
   justify  warrant