Definition: Dodecastylar is a concept in astronomy that refers to the orbits of the planets around the Sun. It was named after the Greek word "dode" (twelve) and "castela" (planet). These orbits are considered to be the only known examples of circular orbits, meaning they do not spiral outwards like other planetary orbits. The dodecastylar system is also known as the "Tetrad" or "Hexadecagon".