planet

noun

Etymology: From Middle English planete, from Old French planete, from Latin planeta, planetes, from Ancient Greek πλανήτης (planḗtēs, “wanderer”) (itself an ellipsis of ἀστέρες πλανῆται (astéres planêtai, “wandering stars”)), from Ancient Greek πλανάω (planáō, “wander about, stray”), of unknown origin. Cognate with Latin pālor (“wander about, stray”), Old Norse flana (“to rush about”), and Norwegian flanta (“to wander about”). More at flaunt. So called because they have apparent motion, unlike the "fixed" stars. Originally including also the moon and sun but not the Earth; modern scientific sense of "world that orbits a star" is from 1630s in English. The Greek word is an enlarged form of πλάνης (plánēs, “who wanders around, wanderer”), also "wandering star, planet", in medicine "unstable temperature." Displaced native Old English tungol.

1. Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.

   “Be they not dreames of humane vanity,[…]to make of our knowne earth a bright shining planet [translating astre]?”

   “The moon[…]began to rise from her bed, where she had slumbered away the day, in order to sit up all night. Jones had not travelled far before he paid his compliments to that beautiful planet, and, turning to his companion, asked him if he had ever beheld so delicious an evening?”

2. Any body that orbits the Sun, including the asteroids (as minor planets) and sometimes the moons of those bodies (as satellite planets)

   “A Discovrse concerning a New Planet. Tending to prove, That 'tis probable our Earth is one of the Planets”

3. A body which is massive enough to be in hydrostatic equilibrium (generally resulting in being an ellipsoid) but not enough to attain nuclear fusion and, in IAU usage, which directly orbits a star (or multiple star) and dominates the region of its orbit; specifically, in the case of the Solar system, the eight major bodies of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

   “Their decision will force a rewrite of science textbooks because the solar system is now a place with eight planets and three newly defined "dwarf planets"—a new category of object that includes Pluto.”

   “The closest planet takes just over nine Earth days to complete an orbit around the star, and the most distant takes about 55 days. All of the planets have quicker revolutions around their star than Mercury, which takes 88 days to complete one lap around the sun.”

4. construed with the or this: The Earth.

   “"My tastes," he said, still smiling, "incline me to the garishly sunlit side of this planet." And, to tease her and arouse her to combat: "I prefer a farandole to a nocturne; I'd rather have a painting than an etching; Mr. Whistler bores me with his monochromatic mud; I don't like dull colours, dull sounds, dull intellects;[…]."”

   “It is tempting to speculate about the incentives or compulsions that might explain why anyone would take to the skies in [the] basket [of a balloon]:[…]; perhaps to moralise on the oneness or fragility of the planet, or to see humanity for the small and circumscribed thing that it is;[…].”