More Google goodness: definitions of words. Search for define polyhedron and get search results with a single (incredibly technical) definition added at the top. Be more specific and search for define:polyhedron, and you get a page with 17 different definitions, from a wide variety of sources. Oddly, dictionary.com doesn't seem to be one of them, since Google can't define triacontahedral, while dictionary.com can: triacontahedral.