surety

noun | \ ˈshu̇r-ə-tē \ | sure·ty
  1. : a formal engagement (as a pledge) given for the fulfillment of an undertaking

  1. : one (as an accommodation party) who promises to answer for the debt or default of another

    Note: At common law a surety is distinguished from a guarantor by being immediately liable as opposed to becoming liable only upon default of the principal. Under the Uniform Commercial Code, however, a surety includes a guarantor, and the two terms are generally interchangeable.