surety

(noun) something clearly established.

(noun) property that your creditor can claim in case you default on your obligation. Synonyms: security. Example: "Bankers are reluctant to lend without good security."

(noun) a prisoner who is held by one party to insure that another party will meet specified terms. Synonyms: hostage.

(noun) one who provides a warrant or guarantee to another. Synonyms: guarantor, warrantor, warranter.

(noun) a guarantee that an obligation will be met. Synonyms: security.