Polychoron

80px4-simplex(5-cell)80px4-orthoplex(16-cell)80px4-cube(Tesseract)80px24-cell80px120-cell80px600-cellGraphs of six convex regular 4-polytope.
250px|thumb|The tesseract is the best known polychoron, containing eight cubic cells, three around each edge.It is viewed here as a Schlegel diagram projection into 3-space, distorting the regularity, but keeping its topological continuity. The eighth cell projects into the volume of space exterior to the boundary.

In geometry, a polychoron (plural: polychora) is a figure in four dimensions. The word comes from Greek poly, which means many and choros which means room, or space. Sometimes the figure is called 4-polytope or polyhedroid. The analogue figure in two dimensions is a polygon, and the one in three dimensions is a polyhedron. 

Other websites

Four dimensional figures page
Jonathan Bowers: Uniform polychora

Category:Shapes