means The large celestial bodies that orbit a star, are massive enough to be rounded by their own gravity, and have cleared their orbital neighborhood of other debris.

from From the Greek 'planetes,' meaning 'wanderer' — because to ancient sky-watchers these were the restless lights that drifted against the fixed backdrop of stars, refusing to stay put night after night. The word traveled through Latin 'planeta' into Old French and finally into English, always carrying that sense of a sky-bound vagabond that wouldn't keep still.