plutoid

The term plutoid has been used minor planets with some particular Pluto-like characteristics. In 2008, the IAU standardized the term such as to encompass Pluto and Eris, essentially defining it as trans-Neptune objects (with orbits beyond Neptune) that are dwarf planets, i.e., that are spherical but not massive enough to clear their neighborhood. Before that standardization, the term sometimes also presumed the body to be icy (an ice dwarf, comprised of frozen volatiles), and may sometimes still be used in such manner. Haumea and Makemake have also sometimes been called plutoids.

A similar term, plutino is defined as "any size or composition", but in a 3:2 orbital resonance with Neptune (as is Pluto), and a twotino is like a plutino except that the resonance is 2:1. Other than Pluto, they are all small objects. Estimates are there are thousands of plutinos.