Guaranty

In law and common usage: An undertaking to answer for the payment of some debt, or the performance of some contract or duty, of another, in case of the failure of such other to pay or perform; a guarantee; a warranty; a security.

In law and common usage: To undertake or engage that another person shall perform (what he has stipulated); to undertake to be answerable for (the debt or default of another); to engage to answer for the performance of (some promise or duty by another) in case of a failure by the latter to perform; to undertake to secure (something) to another, as in the case of a contingency. See Guarantee, v. t.

a collateral agreement to answer for the debt of another in case that person defaults