Which geometric term best describes a solid object with flat surfaces and a defined volume?

The term "solid" is best used to describe a three-dimensional object that occupies space and has a defined volume. Solids are characterized by having length, width, and height, and they possess a specific shape and form that is maintained regardless of their position.

For instance, common examples of solids include cubes, spheres, and pyramids, all of which have flat surfaces, edges, and vertices. This distinguishes them from other geometric classifications. By defining volume, a solid object can be measured in cubic units, reflecting the space it takes up in three dimensions. Thus, referring to a solid as having "flat surfaces" and a "defined volume" aligns perfectly with the geometric definition of solids.

In contrast, a plane refers to a flat, two-dimensional surface that lacks depth, making it incompatible with the description of a solid. "Linear" describes a one-dimensional aspect, such as a line, and "curved" refers to surfaces that are not flat, such as spheres or cylinders, which do not meet the criteria of having only flat surfaces. Hence, solid is the most accurate term here.