A guarantee is a promise or ASSURANCE that certain conditions will be fulfilled. An OATH is a solemn promise to be honest or to fulfill an obligation. A SEAL is an official mark or stamp that is used to authenticate documents. A DEPOSIT is money or other assets placed in a bank or other financial institution. BAIL is money or property given to a court as a guarantee that a person accused of a crime will appear in court when required. A STAKE is an investment or risk taken in the hope of gaining a profit or advantage. INSURANCE is a contract that provides PROTECTION against loss or damage. ATTEST is to certify as true or genuine. ENDORSE is to approve or support something. PROTECTION is the act of guarding someone or something from harm or danger. SAFEGUARD is a measure taken to protect someone or something from harm or danger. UNDERWRITE is to accept financial responsibility for something. To SWEAR is to make a solemn promise or statement. To VOUCH is to provide evidence or testimony in support of something. ASSURE is to state something confidently and forcefully in order to give someone reassurance. AVOUCH is to declare or affirm something as true. ENSURE is to make certain that something will happen or be the case. INSURE is to provide INSURANCE for something. PLEDGE is to make a solemn promise or agreement. SECURE is to make something safe or protected. SURETY is a guarantee of the performance of a person's obligations. A surebet is a bet that is guaranteed to win. Makesure is to make certain that something is done. Vouchfor is to provide evidence or testimony in support of someone. ASSURANCE is a promise or guarantee that something will happen or be the case.