Kuiper belt object
Kuiper belt object definition by American Heritage Dictionary
noun Abbr. KBO
Any of the small icy bodies orbiting the sun in the Kuiper belt, generally having a diameter less than Pluto's. Pluto is a large Kuiper belt object that was probably captured in its present solar orbit by an encounter with the planet Neptune.
Origin: After Gerard Kuiper (1905-1973), Dutch-born American astronomer who speculated about the existence of such bodies.