Wiktionary
n. (context astronomy English) Any of several planetoids in the Kuiper Belt that have orbits similar to Pluto in that they have a resonance of 3:2 with that of Neptune
Wikipedia
In astronomy, a plutino is a trans-Neptunian object in 2:3 mean-motion resonance with Neptune. For every 2 orbits that a plutino makes, Neptune orbits 3 times. The term "plutino" derived from the dwarf planet Pluto, the largest and the first plutino discovered. The term does not imply common physical characteristics. Plutinos are named after mythological creatures associated with the underworld.
Plutinos form the inner part of the Kuiper belt and represent about a quarter of the known Kuiper belt objects (KBOs). Plutinos are the largest class of the resonant trans-Neptunian objects (i.e. bodies in orbital resonances with Neptune).
Aside from Pluto itself, the first plutino, (385185) 1993 RO, was discovered on September 16, 1993.
Usage examples of "plutino".
December 2002 had found over six hundred additional Trans-Neptunian Objects, or Plutinos as they are alternatively called.
From the terrace road along the shore, Via Plutino, beauties and glories indescribable lie before one at every turn of the head.