The software comes with a 'money-back guarantee'. [=a promise that the money you spend on a product will be returned if the product is not good enough]
We used our house as a 'guarantee' for the loan. [=we said that the bank could take our house if we did not pay back the loan]
There is no 'guarantee' that they will approve the contract. [=there is no way to be sure that they will approve it]
(..) l'm gonna blow my brains out right on the air... right in the middle of the seven o'clock news. You'll get a hell of a rating, l'll guarantee that. Fifty share easy. - You think so? - Sure. We could make a series out of it. "Suicide of the Week." (..)1976 Network