I've got no business even being in this discussion, but reading all the other posts about how one distinguishes what's out there in the ether I've come up with a set of daffynitions that works for me, albeit I'm willing to accept that it might be too naive for real working astronomers:

A planetary object is any orbiting body whose primary is a star (or possibly brown dwarf, I'm open-minded about that); a moon is any orbiting body whose primary is a planetary object. A planet is a planetary object which does not share its general orbit (note: not specific orbit, since each asteroid has its own peculiar orbit) with other planetary objects; a planetoid is a planetary object which shares a general orbital area with other planetary objects (i.e., other planetoids)--moons don't count for this distinction (i.e., a planet can have moons without them making it a planetoid).

Thus the denizens of the Asteroid Belt and the Kuyper Belt both classify as planetoids, and the only distinction is "inner belt" v. "outer belt". Pluto/Charon are planetoids by this definition.

The reason I say I don't really belong in this discussion is that I don't know/understand enough about the whole zoo of other "thingies" floating around out there. Are there other "Trans-Neptunian" bodies besides Pluto/Charon and the Kuyper Belt? P/C doesn't come anywhere close to the Kuyper as I understand it, so if the only usefulness of the TNO designation is to group P/C with the KB then I'm agin it, as Granny would say.

I also realise that my classification doesn't do real good with non-belted asteroids, such as cross the Earth's orbit or Jupiter's Trojans. Come to that, a strict application of my definition to Jupiter would make it a planetoid, too, due to those very same Trojans, so I guess some sort of size distinction is necessary as well (i.e., one huge planetary object sharing its orbit with a bunch of smaller critters is a planet and the small junk are planetoids, whereas they're all planetoids if they're all close to the same size [within one order of magnitude, say]).

Well, as I say it's just an amateur's opinion. (I'm deprecating it mainly because the more I think it through myself, the less impressed with it I am.)

The (still orbiting the eggnog) Curtmudgeon