A world-like planetoid of the Solar system, that is smaller than the classical planets. More specifically, any astronomical body which has a geology defined by hydrostatic equilibrium (and thus has taken the shape a body of water would take, as opposed to a small Solar System body), orbits the Sun (as opposed to a moon), and does not gravitationally dominate other bodies near its orbit (as opposed to a classical planet or, in IAU usage, as opposed to a planet).