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]
(..) We know this world revolves around Toretto, right? I'm not saying that he's the one that's popping these trucks... ...but I can guarantee he knows who is. It's just a matter of time until I win-- You want time, buy the magazine. We don't have time. Just get me something I can use. (..)2001 The Fast and the Furious