What aspect of metalwork is defined by a hollow cavity used in casting?

The aspect of metalwork that is defined by a hollow cavity used in casting is referred to as a mold. A mold serves as a form into which molten metal is poured to create a specific shape or design as it cools and solidifies. Molds can be made from various materials, including metal, sand, or plaster, and they are essential for the casting process, allowing for the production of complex shapes that would be difficult to achieve through other manufacturing methods.

Understanding the role of molds in metal casting is critical, as they directly influence the quality and accuracy of the cast parts. The hollow cavity in the mold replicates the desired final product, so the design and quality of the mold are paramount for achieving precise dimensions and surface finishes in the finished part.