What is a casket commonly defined as?

A casket is commonly defined as a rigid container that is specifically designed for the encasement of human remains. This definition encompasses the primary function of a casket, which is to hold and protect the deceased until burial or cremation. Caskets are typically constructed from materials such as wood or metal and are often chosen based on the preferences of the deceased's family or cultural practices.

The other options represent different aspects of funerary customs but do not accurately define what a casket is. A decorative urn for ashes refers to a container used to hold cremated remains, distinct from a casket. A burial plot is a designated piece of land where remains are interred, while a memorial stone is used to commemorate the deceased but is not a container for the remains themselves. Hence, the correct answer emphasizes the specific purpose and design of a casket in the context of funerary practices.