What aspect of building materials does the term "cornice" signify?

The term "cornice" refers specifically to a decorative feature that runs along the top edge of a wall, often serving a dual purpose of both aesthetic appeal and practical function. While its primary role is to enhance the visual impact of a building's silhouette by adding depth and interest, it also serves as a support ledge. This ledge can help to direct rainwater away from the building's walls, thereby contributing to its overall integrity and longevity.

In architecture, cornices are commonly found at the junction of the wall and the roof, acting as an eave. They can help in preventing water from running down the walls, protecting the building's structure. This functional aspect affirms that cornices are not only decorative elements but also have practical implications for the durability of the building, aligning with the correct choice of support ledge as the defining characteristic. Other options, while related to building materials and components, do not capture the dual role of cornices as effectively as the notion of a support ledge does.