Wafer

In microelectronics, a wafer is a thin slice of semiconducting material, such as a silicon crystal, upon which microcircuits are constructed by diffusion and deposition of various materials.

Note: Millions of individual circuit elements, constituting hundreds of microcircuits, may be constructed on a single wafer. The individual microcircuits are separated by scoring and breaking the wafer into individual chips ("dice").

Source: from Federal Standard 1037C

In cooking, a wafer can refer to a crisp, sweet, very thin flat dry cake which is often used to decorate icecreams, can be made into biscuits with cream flavoring sandwiched between them, or special wafers can be made for Catholic Holy Communion services.