Neptunian

[ nep-too-nee-uh n, -tyoo- ]

/ nɛpˈtu ni ən, -ˈtyu- /

pertaining to Neptune or the sea.

pertaining to the planet Neptune.

(often lowercase) Geology. formed by the action of water.

Origin of Neptunian

First recorded in 1650–60; Neptune + -ian

trans-Nep·tu·ni·an, adjective

The Neptunian leader began to gesture again, and conveyed to Burl that they wanted to attack as soon as possible.

The Secret of the Ninth Planet |Donald Allen Wollheim
The rocks thus deposited were called Neptunian by the older geologists.

The World Before the Deluge |Louis Figuier
There was nothing to do then but to join the Neptunian assault.

The Secret of the Ninth Planet |Donald Allen Wollheim
It passes here, under the fanciful name of Neptunian Goblet.

The Mission to Siam, and Hu the Capital of Cochin China, in the Years 1821-2 |George Finlayson

Though the account is very interesting, I do not perceive its exact bearing on the Neptunian and Plutonian hypotheses.

Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 |Henry Rowe Schoolcraft

Neptunian

/ (nɛpˈtjuːnɪən) /

of or relating to the Roman god Neptune or the sea

of, occurring on, or relating to the planet Neptune

geology (of sedimentary rock formations such as dykes) formed under water