2. (Science: astronomy) The remotest known planet of our system, discovered as a result of the computations of Leverrier, of paris by Galle, of Berlin, september 23. 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.
Origin: L. Neptunus.