Merriam-Webster Collegiate Dictionary - planet

 noun  Etymology: Middle English ~e, from Anglo-French, from Late Latin ~a, modification of Greek planet-, planes, literally, wanderer, from planasthai to wander — more at floor  Date: 13th century  1.  a. any of the seven celestial bodies sun, moon, Venus, Jupiter, Mars, Mercury, and Saturn that in ancient belief have motions of their own among the fixed stars  b.  (1) any of the large bodies that revolve around the sun in the solar system  (2) a similar body associated with another star  c. earth — usually used with the  2. a celestial body held to influence the fate of human beings  3. a person or thing of great importance ; luminary  • ~like adjective