Using a set of corners of a Solid that lie in a plane to form the Vertices of a new Polygon is called faceting. Such Polygons may outline new Faces that join to enclose a new Solid, even if the sides of the Polygons do not fall along Edges of the original Solid.
Holden, A. Shapes, Space, and Symmetry. New York: Columbia University Press, p. 94, 1971.