Pluto

[ ploo-toh ]
/ ˈplu toʊ /
|

noun

Classical Mythology. a name given to Hades, under which he is identified by the Romans with Orcus.
Astronomy. a dwarf planet having an equatorial diameter of about 2100 miles (3300 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. Until 2006, Pluto was classified as a planet ninth in order from the sun; the International Astronomical Union has reclassified it as a dwarf planet.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for pluto

British Dictionary definitions for pluto (1 of 3)

Pluto

1
/ (ˈpluːtəʊ) /

noun

classical myth the god of the underworld; Hades

British Dictionary definitions for pluto (2 of 3)

Pluto

2
/ (ˈpluːtəʊ) /

noun

the second-largest dwarf planet in the solar system, located in the Kuiper belt; discovered in 1930 by Clyde Tombaugh (1906–97); classified as a planet until 2006, when it was reclassified as a dwarf planet. It has a diameter of 2390 km

Word Origin for Pluto

Latin, from Greek Ploutōn, literally: the rich one

British Dictionary definitions for pluto (3 of 3)

PLUTO

/ (ˈpluːtəʊ) /

noun

the code name of pipelines laid under the English Channel to supply fuel to the Allied forces landing in Normandy in 1944

Word Origin for PLUTO

C20: from p (ipe) l (ine) u (nder) t (he) o (cean)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for pluto

Pluto


n.

Roman god of the underworld, brother of Zeus and Neptune, from Latin Pluto, Pluton, from Greek Plouton "god of wealth," literally "wealth, riches," probably originally "overflowing," from PIE *pleu- "to flow" (see pluvial). The planet (since downgraded) was discovered 1930 by C.W. Tombaugh; Minerva also was suggested as a name for it. The cartoon dog first appeared in Walt Disney's "Moose Hunt," released April 1931.

Online Etymology Dictionary, © 2010 Douglas Harper

Science definitions for pluto

Pluto

[ plōōtō ]

A dwarf planet that until 2006 was classified as the ninth planet in the Solar System. Pluto was not discovered until 1930, when Clyde Tombaugh noticed it while searching for an unknown planet thought to influence Uranus's orbit. Pluto's surface is covered with frozen methane and other ices, and its extremely thin atmosphere consists primarily of methane and nitrogen. Between 1979 and 1999 Pluto crossed inside Neptune's orbit. Pluto has three moons: Charon (discovered in 1978) and Hydra and Nix (both discovered in 2005). See Table at solar system.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for pluto (1 of 2)

Pluto


The Roman name of Hades, the Greek and Roman god of the underworld and ruler of the dead.

Note

The planet Pluto is usually the most distant planet in the solar system.

Culture definitions for pluto (2 of 2)

Pluto


In astronomy, the smallest of the major planets, usually ninth from the sun. Pluto was discovered in 1930 and is named for the Roman god of the underworld. (See solar system)

Note

Astronomers in the late nineteenth century, thinking they saw disturbances in the orbits of Uranus and Neptune, suspected that there was a ninth planet, not yet discovered, exerting gravitation on the other two. In the early twentieth century, astronomers searched for that planet and found Pluto. Ironically, Pluto is much too small to be the planet they sought.

Note

Pluto's orbit is a stretched ellipse, unlike the orbits of the other major planets, which are nearly circular. As a result, for a period ending in 1999, Pluto was actually closer to the sun than Neptune.

Note

There is some debate among astronomers as to whether Pluto should really be classified as a planet or should instead be considered a large asteroid-like body.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.