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

Named after the Roman god of the sea, Neptune is a world of powerful storms, deep mysteries, and breathtaking beauty. —Kenna Hughes-Castleberry, Space.com, 30 Aug. 2025

Those three naked-eye planers are joined by Neptune (close to Saturn) and Uranus, though both of those outer planets are impossible to see with the naked eye. —Jamie Carter, Forbes.com, 29 Aug. 2025

Snap a photo with the 24-foot-tall King Neptune statue, which sits on the boardwalk at the entrance of Neptune Park. —Tara Massouleh McCay, Southern Living, 28 Aug. 2025

Uranus harmonizing with Neptune says to boldly envision together instead of playing it safe. —Usa Today, USA Today, 28 Aug. 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