Planetoids:
The International Astronomical Union (IAU) developed some definitions in 2001, and then modified them again in 2003. Under their definition, planets are any objects orbiting stars or stellar remnants (like pulsars) which are below the limiting mass for thermonuclear fusion of deuterium. This sets an upper limit at about 13 times the mass of Jupiter.
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As new claims are made in the future, the WGESP will weigh their individual merits and circumstances, and will try to fit the new objects into the WGESP definition of a "planet", revising this definition as necessary. The WGESP has agreed to the following statements:
1) Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.
2) Objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how they formed or where they are located.
3) Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or most appropriate name).
These statements are a compromise between definitions based purely on the deuterium-burning mass, or on the formation mechanism, and as such, do not fully satisfy anyone on the WGESP. However, the WGESP agrees that these statements constitute the basis for a reasonable working definition of a "planet" at this time. We can expect this definition to evolve as our knowledge improves.