- noun a zone beyond the orbits of Neptune and Pluto, some 30–60 AU distant and mainly in the plane of the ecliptic, in which many millions of comets are postulated to exist
- Zone beyond the orbits of Neptune, some 30–60AU and mainly in the plane of the ecliptic, in which many millions of comets are postulated to exist. Some possible Kuiper Belt comets have been observed. The short-period comets that enter the inner solar system may be Kuiper Belt members whose orbits have been perturbed. The Kuiper Belt would form an intermediate comet group between the Oort Cloud and the Sun.