1. General: Written undertaking that something is of a specified benefit, content, or quality, or that it will provide satisfaction or will perform a duty or obligation in a specified manner.

2. Legal: Three-party contingent liability agreement under which a third-party (the guarantor) agrees to be directly or collaterally responsible for the obligation (contract fulfillment, loan) of a first-party (the principal) to a second-party (bank, client) in case the first-party defaults or fails to fulfil its part of a deal. In effect, signing a guaranty as a guarantor is like signing a blank check. Unlike a warranty, a guaranty may refer to things as well as persons and, to be legally enforceable, must be in writing. Also called bond.