An ancient three letter acronym, standing for Metro-Goldwyn-Mayer. The Goldwyn was Samuel and the Mayer was Louis B. One of the huge filmstudios (trademark: a roaring lion) that put Hollywood on the map. Made famous in later decades by the nostalgia boom of the 70s, and a documentary called That's Entertainment!, showcasing the classic musicals MGM made. Via mergers and acquisitions, much of their library ended up in Ted Turner's hands - it forms the core of Turner Classic Movies.