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]
(..) I'd like a little pin from the Pope. Sure, I take the Blacks and the Spanish into my family, because that's America. And you guarantee that they don't deal drugs? I don't guarantee that. I guarantee that I'll kill anybody who does. - Let me talk to him. - Who can refuse Don Altobello? (..)1990 The Godfather Part III