In solid geometry, a **prismatic surface** is a polyhedral surface
generated by all the lines that are parallel to a given line and that intersect a Polygonal chain in a plane that is not parallel to the given line.^{[1]} The polygonal chain is the *directrix* of the surface; the parallel lines are its *generators* (or *elements*). If the directrix is a convex polygon, then the surface is a *closed prismatic surface*. The part of a closed prismatic surface between two parallel copies of the directrix is a prism.^{[2]}