Complex sentence: A regular dodecahedron or pentagonal dodecahedron is a dodecahedron that is regular composed of twelve regular pentagonal faces, with three meeting at each vertex, and is represented by the Schläfli symbol.
Split into simpler sentences: A regular dodecahedron or pentagonal dodecahedron is a dodecahedron that is regular. It is composed of twelve regular pentagonal faces, with three meeting at each vertex, and is represented by the Schläfli symbol.