If one thing guarantees another, the first is certain to cause the second thing to happen.

Something that is a guarantee of something else makes it certain that it will happen or that it is true.

If you guarantee something, you promise that it will definitely happen, or that you will do or provide it for someone.

A guarantee is a written promise by a company to replace or repair a product free of charge if it has any faults within a particular time.

If a company guarantees its product or work, they provide a guarantee for it.

A guarantee is money or something valuable which you give to someone to show that you will do what you have promised.