Hades three-headed guard dog Cerberus. The Etruscan god Aita and the Roman gods Dis Pater and Orcus were eventually taken as equivalent to Hades and merged into Pluto, a Latinization of Plouton (", Ploútōn"), itself a euphemistic title often given to Hades. The origin of Hades' name is uncertain, but has generally been seen as meaning "the unseen one" since antiquity. An extensive section of Plato's dialogue "Cratylus" is devoted to the etymology of the god's name, in which Socrates is arguing for a folk etymology not from "unseen" but from "his knowledge ("eidenai") of all noble things". Modern linguists have
90482 Orcus of death, and frequently acted as a guide of the deceased to the underworld. The absolute magnitude of Orcus is approximately 2.3 (comparable with the 2.6 of cubewano 50000 Quaoar). The detection of Orcus by the Spitzer Space Telescope in the far infrared and by Herschel Space Telescope in submillimeter constrains its diameter to . Orcus appears to have an albedo of about 21% to 25%, which may be typical of trans-Neptunian objects approaching the 1000 km diameter range. In the magnitude and size estimates reported above it was assumed that Orcus is a singular object. The presence of a