surety
n. C / Un. a person or company that promises to pay a debt if someone else cannot. It is like a guarantee that the money will be there if you need it.
n. a person or entity that provides a guarantee or security for the performance of a debt or obligation. Often used in legal contexts to describe a third-party guarantee of payment.
The bank requires a surety for the large loan.
Before the contract was signed, the contractor had to provide a surety to ensure the project would be completed on time.
In international trade, a bank acting as a surety provides a financial guarantee that the buyer will pay for the goods, protecting the seller against the risk of non-payment.
From Middle English surete, attested since the early 1300s in the sense "guarantee, promise, pledge, assurance", from Anglo-Norman seurté/Old French seurté with the same meaning (whence modern French sûreté), from Latin sēcūritās. Equivalent to sure + -ty. The senses "security, safety, stability" and "certainty" are attested since the late 1300s. "One who undertakes to pay if another does not" is from the early 1400s. Doublet of security.