the ancient Roman god of the sea, identified with the Greek god Poseidon.
the sea or ocean.
Neptune's mighty roar.
Astronomy. the planet eighth in order from the sun, having an equatorial diameter of 30,200 miles (48,600 km), a mean distance from the sun of 2794.4 million miles (4497.1 million km), a period of revolution of 164.81 years, and two moons.
a township in E New Jersey.
The eighth planet from the Sun and the fourth largest, with a diameter almost four times that of Earth. Neptune is a gas giant with a very active weather system, exhibiting extremely long and powerful storms with the fastest winds observed in the solar system. Neptune's axis is tilted 28.8° from the plane of its orbit, and its summer and winter seasons each last 40 years. For a period of 20 years out of every 248, Pluto's highly elliptical orbit crosses within that of Neptune. Neptune has four faint rings and 13 known moons and appears blue due to the absorption of red light by the methane within its atmosphere.
See Table at solar system
The eighth planet from the sun (the Earth is third) is named Neptune.
Neptune is frequently portrayed as a bearded giant with a fish's scaly tail, holding a large three-pronged spear, or trident.
Some astronomers have suggested that Pluto is not a planet in the usual sense but is an object more like an asteroid, and that Neptune, therefore, is actually the outermost planet.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Vance said the most promising of the cultivars are neptune, a green grape from Arkansas with high yields year after year; canadice, a smaller red grape from Cornell with good flavor and uniform clusters.
From Washington Times ● Mar. 18, 2017
They gather it in the forest, especially during the dries, collect it in hollow bamboos, and prepare it by heating in the neptune, or brass pan.
From Two Trips to Gorilla Land and the Cataracts of the Congo Volume 1 by Burton, Richard Francis, Sir
Weir and a small crew are sent on a recovery mission after the lost spaceship, the Event Horizon, suddenly reappears in orbit around Neptune, issuing a distress signal.
From Salon ● Jul. 17, 2026
Chris Long, intelligence director at U.K. maritime-security company Neptune P2P Group, who advises shippers crossing through the strait, said the strike had halted a recovery in transits.
From The Wall Street Journal ● Jun. 26, 2026
The deep interiors of ice giant planets such as Uranus and Neptune may contain a previously unknown form of matter.
From Science Daily ● Apr. 21, 2026
These properties are especially important for understanding how Uranus and Neptune generate their magnetic fields, which differ in unusual ways from those of other planets.
From Science Daily ● Apr. 21, 2026
“The gift of Periclymenus... I think, I think he was a son of Poseidon, I mean Neptune, I mean...”
From "The Son of Neptune" by Rick Riordan
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
