<p><strong>noun</strong></p><ul><li>In Classical Mythology: a name given to Hades, under which he is identified by the Romans with Orcus.</li><li>In Astronomy: a dwarf planet having an equatorial diameter of about 2,100 miles (3,300 km), a mean distance from the sun of 3.674 billion miles (5.914 billion km), a period of revolution of 248.53 years, and one known moon, Charon.</li><li>Based on the definition of a planet devised by the International Astronomical Union in 2006, Pluto, regarded as the ninth and most distant planet in our solar system since its discovery in 1930, was reclassified as a dwarf planet, a decision that continues to be examined and questioned by some astronomers.</li></ul><p><strong>End of Response</strong></p>