Side

In geometry, a side is a line that is part of a flat figure made from straight lines. It is also a face in a solid three-dimensional object. The number of sides in a polygon is often written as ${\displaystyle n}$, while the number of faces in a polyhedron is often written as ${\displaystyle F}$.

As an example, the square on the right has four sides. The sides in this picture are made with black straight lines. The four sides are: