Nep″tune (?), n. [L. Neptunus.] 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.
Neptune powder, an explosive containing nitroglycerin, — used in blasting. — Neptune's cup(Zoöl.), a very large, cup-shaped, marine sponge (Thalassema Neptuni).