What is the name for a shape with eight sides?

A shape with eight sides is called an octagon. The terminology for shapes is derived from Greek prefixes, where "octa-" means eight. This prefix is essential for identifying the number of sides a polygon has. For example, an octagon has eight straight edges and vertices.

To add context, a hexagon is a six-sided shape, a heptagon has seven sides, and a decagon is a ten-sided figure. Knowing these prefixes helps to accurately name polygons based on the number of sides they possess. Thus, understanding that "octagon" refers specifically to the eight-sided figure is crucial in geometry.