In
geometry, an
edge is a particular type of
line segment joining two
vertices in a
polygon,
polyhedron, or higher-dimensional
polytope. In a polygon, an edge is a line segment on the boundary, and is often called a
side. (Thus a segment joining two vertices while passing through the interior or exterior is not an edge but instead is called a
diagonal.) In a polyhedron or more generally a polytope, an edge is a line segment where two two-dimensional faces meet.