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a. Roman Mythology The god of water, later identified with the Greek Poseidon.
b. The sea.
2. The eighth planet from the sun, having a sidereal period of revolution around the sun of 164.8 years at a mean distance of 4.5 billion kilometers (2.8 billion miles), a mean equatorial diameter of 49,528 kilometers (30,775 miles), and a mass 17.25 times that of Earth.
Nep·tu′ni·an (-to͞o′nē-ən, -tyo͞o′-) adj.
(Classical Myth & Legend) the Roman god of the sea. Greek counterpart: Poseidon
(Astronomy) the eighth planet from the sun, having fourteen known satellites, the largest being Triton and Nereid, and a faint planar system of rings or ring fragments. Mean distance from sun: 4497 million km; period of revolution around sun: 164.8 years; period of rotation: 14 to 16 hours; diameter and mass: 4.0 and 17.2 times that of earth respectively
Nep•tune(ˈnɛp tun, -tyun)
1. the Roman god of the sea, identified with the Greek god Poseidon.
2. the sea or ocean: Neptune's mighty roar.
3. the planet eighth in order from the sun, having an equatorial diameter of 30,200 mi. (48,600 km), a mean distance from the sun of 2794.4 million mi. (4497.1 million km), a period of revolution of 164.81 years, and at least six moons.
The eighth planet from the sun and the fourth largest, with a diameter almost four times that of Earth. Neptune has a very active weather system with extremely long and powerful storms. It is the coldest planet in the solar system, with an average surface temperature of -330°F (-201°C). See Table at solar system. See Note at planet.
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|Noun||1.||Neptune - (Roman mythology) god of the sea; counterpart of Greek Poseidon|
Roman mythology - the mythology of the ancient Romans
|2.||Neptune - a giant planet with a ring of ice particles; the 8th planet from the sun is the most remote of the gas giants; "the existence of Neptune was predicted from perturbations in the orbit of Uranus and it was then identified in 1846"|
solar system - the sun with the celestial bodies that revolve around it in its gravitational field