Another word for guarantee
attest, testify, aver, vouch for, declare, assure, ensure, answer for, be responsible for, stand behind, become surety for, evince, evidence, endorse, secure, make sure, make certain, warrant, insure, witness, prove, reassure, support, affirm, confirm.
To give security
Another word for guaranteenoun
An assumption of responsibility, as one given by a manufacturer, for the quality, worth, or durability of a product:guaranty, surety, warrant, warranty. See obligation
A declaration that one will or will not do a certain thing:assurance, covenant, engagement, guaranty, pledge, plight2, promise, solemn word, vow, warrant, word, word of honor. See obligation