1.Roman Mythology The god of the dead and the ruler of the underworld. 2. The ninth and usually farthest planet from the sun, having a sidereal period of revolution about the sun of 248.5 years, 4.4 billion kilometers (2.8 billion miles) distant at perihelion and 7.4 billion kilometers (4.6 billion miles) at aphelion, and a diameter less than half that of Earth.
ETYMOLOGY:
Latin Plt, Pltn-, from Greek Ploutn, from ploutos, wealth (from the belief that the underworld was the source of wealth from the ground). See pleu- in Appendix I.
pl
t
t
