neptune Meaning, Definition & Usage

  1. noun (Roman mythology) god of the sea; counterpart of Greek Poseidon
  2. noun 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

WordNet

Nep"tune noun
Etymology
L. Neptunus.
Definitions
  1. (Rom. Myth.) The son of Saturn and Ops, the god of the waters, especially of the sea. He is represented as bearing a trident for a scepter.
  2. (Astron.) The remotest known planet of our system, discovered -- as a result of the computations of Leverrier, of Paris -- by Galle, of Berlin, September 23, 1846. Its mean distance from the sun is about 2,775,000,000 miles, and its period of revolution is about 164,78 years.

Webster 1913