Neptune

noun

Nep·​tune ˈnep-ˌtün 

-ˌtyün

1

a

: the Roman god of the sea compare poseidon

b

: ocean

2

: the planet eighth in order from the sun see Planets Table

Neptunian

nep-ˈtü-nē-ən 

-ˈtyü-

adjective

Synonyms

• sea
• ocean

Examples of Neptune in a Sentence

sailors shipwrecked by the wild waves of Neptune

Recent Examples on the Web

The father and son are suspected of spying on Ukraine's Neptune anti-ship missile program. —Shane Croucher, MSNBC Newsweek, 10 July 2025

Although the Capricorn full moon comes across as rather serious, there is a connection between Saturn—the ruling planet of Capricorn—and Neptune and Pluto, both retrograde, at the time of its occurrence. —Danijela Pilic, Glamour, 10 July 2025

In recent months, Saturn put on a spectacular show for early risers, who witnessed the gas giant climb over the eastern horizon just ahead of sunrise, often in close proximity to Venus, Mercury and dimmer Neptune. —Anthony Wood, Space.com, 9 July 2025

See Saturn, Neptune and the moon align Amateur astronomers can witness a rare alignment of planets and the moon in the early hours ahead of dawn on Wednesday, July 16. —Hannah Poukish july 8, Sacbee.com, 8 July 2025

Word History

Etymology

Latin Neptunus

First Known Use

before the 12th century, in the meaning defined at sense 1a

Kids Definition

Neptune

noun

Nep·​tune ˈnep-ˌt(y)ün 

: the planet eighth in order from the sun see planet

Neptunian

nep-ˈt(y)ü-nē-ən 

adjective