What shape is a casket that has eight angles or corners?

A casket with eight angles or corners is described as having an octagonal shape. The term "octagon" refers specifically to a polygon with eight sides and eight angles. Each angle of an octagon contributes to the total of eight distinct corners, making it the appropriate descriptor for such a shape.

In contrast, other options represent different shapes with fewer or greater angles. A hexagon has six angles, a quadrilateral has four, and a decagon consists of ten angles, each of these defining features distinctly separate from the characteristics of an octagon. Thus, when identifying a shape with exactly eight angles, the octagon is the definitive choice.