planetoid

1. (astronomy, dated) An asteroid of any sizeExamples: "The group of small bodies that circle round the Sun, outside the orbit of Mars, are known under the designation of the planetoids."; "Numbering of the Planetoids or Asteroidal Planets.—In numbering the planetoids a difficulty has arisen [...]"; "if one can argue for the early existence of a few largely molten planetoids with dimension of kilometers or tens of kilometers, one can quite as easily argue for very large numbers of such planetoids."dated

2. (astronomy, dated) An asteroid-like body in an orbit beyond the asteroid belt, such as a centaur or Kuiper belt objectdated

3. (astronomy) A larger, planetary, body in orbit around the Sun, such as Vesta or (candidate) dwarf planets such Eris or SednaExamples: "After discovering "planetoids", bodies orbiting the Sun, even larger than Pluto's moon Charon ... the question of how Sedna and other planetoids came to be."; "Eris [...] was the upstart planetoid that knocked Pluto off the planetary lists"

4. (astronomy) Any planetary body, including classical planets and moons: a planetary-mass objectExamples: "Plate tectonics is a style of convection for an active planetoid where lid fragment (plate) motions reflect sinking of dense lithosphere in subduction zones […] In 2015 humanity completed a 50+ year effort to survey the 30 largest planets, asteroids, satellites, and inner Kuiper Belt objects, which we informally call “planetoids”."

5. (astronomy) A dwarf planetExamples: "We prefer the word "planetoid" as a new word to describe round objects orbiting the sun."; "A dwarf planet or a planetoid is a celestial body that [...]"; "'Dwarf planet' is a dumb phrase. For years we've called things like Pluto and Xena 'planetoids'—planetlike."