Complex sentence: In geometry, a four-dimensional polytope or 4-polytope is a connected and closed figure composed of lower dimensional polytopal elements: vertices, edges, faces (polygons), and cells (polyhedra).
Split into simpler sentences: In geometry, a polychoron or 4-polytope is a four-dimensional polytope. It is a connected and closed figure, composed of lower dimensional polytopal elements: vertices, edges, faces (polygons), and cells (polyhedra).