From Middle English Neptunus, a borrowing from Latin Neptūnus, from Proto-Indo-European *nébʰ-tu-s (“to become damp, cloudy”) (source of Ancient Greek νέφος (néphos), Sanskrit नभस् (nábhas), etc.), with the sense of "wet, moist." Puhvel, however, connects it with Proto-Italic *nepōts from Proto-Indo-European *népōts by analogy to Portūnus, cognate with Vedic Apām Napāt and Avestan Apąm Napāt, Child (cf: neve, nephew) of the Water as part of an Indo-European 'Fire in the Water' myth.
- The eighth planet in our solar system, represented in astronomy and astrology by ♆.
- (Roman mythology) The god of the ocean and of earthquakes. The same as Poseidon in Greek mythology.
- An unincorporated community in West Virginia.
- An unincorporated community in Wisconsin.
- (planets of the Solar System) planets of the Solar System; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune