plutoid

The term plutoid has been used minor planets with some particular Pluto-like characteristics. The International Astronomical Union (IAU) announced, but then retracted a specific "official" definition of plutoid, effectively as a dwarf planet that is also a trans-Neptune object. Other uses of the term have varied, such as presuming the body to be icy (an ice dwarf, comprised of frozen volatiles). Haumea and Makemake have also sometimes been called plutoids.

The IAU announced the above-definition during (following?) a 2008 general meeting, but in fact, its proper division responsible for such terminology, IAU's Working Group for Small Bodies Nomenclature (WG-PSN), had not been consulted, and the declaration was retracted that same year.

A similar term, plutino is used for "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.