What term describes the promise made by a surety in a bond?

The most appropriate term that describes the promise made by a surety in a bond is the principal. In the context of surety bonds, the principal is the party that agrees to fulfill an obligation, which is often a contractual requirement. The surety, who is a third party, guarantees that the principal will meet their obligations; if the principal fails to do so, the surety is responsible for fulfilling that obligation, typically by compensating the obligee, the party that receives the benefit of the bond.

The concepts of guarantee and obligation are related but do not fully capture the specific role of a principal in a bond arrangement. The condition may refer to stipulations outlined in the bond agreement but does not define the party making the promise. Hence, principal is the term that precisely identifies the promisor within the surety bond context.