Neptunian

noun

1. Rom. Myth. the god of the sea: identified with the Greek Poseidon
2. the sea personified
3. the fourth largest planet of the solar system and normally the eighth in distance from the sun: it has a thin, icy ring system around its equator: diameter, c. 49,530 km (c. 30,780 mi); period of revolution, 164.79 earth years; period of rotation, 16.11 hours; 13 satellites; symbol, ♆