Plu·​to | \ ˈplü-(ˌ)tō How to pronounce Pluto (audio) \

Definition of Pluto

1 : the Greek god of the underworld — compare dis
2 [New Latin] : a dwarf planet occupying an orbit that crosses the orbit of Neptune

Is Pluto a planet?: Usage Guide

In 2006 the International Astronomical Union defined planet in such a way as to exclude Pluto, reclassifying it instead as a dwarf planet. Although discussion of the matter continues, the change has been widely accepted.

First Known Use of Pluto

14th century, in the meaning defined at sense 1

History and Etymology for Pluto

Latin Pluton-, Pluto, from Greek Ploutōn

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Time Traveler for Pluto

Time Traveler

The first known use of Pluto was in the 14th century

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Cite this Entry

“Pluto.” Dictionary, Merriam-Webster, Accessed 8 May. 2021.

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English Language Learners Definition of Pluto

: the object in our solar system that in the past was thought to be the planet farthest from the sun but that is no longer considered to be a planet


Plu·​to | \ ˈplü-tō How to pronounce Pluto (audio) \

Kids Definition of Pluto

: a celestial object that orbits the sun at an average distance of 3.7 million miles (5.9 million kilometers) and has a diameter of about 1500 miles (2300 kilometers) and is often considered one of the planets

More from Merriam-Webster on Pluto

Nglish: Translation of Pluto for Spanish Speakers

Britannica English: Translation of Pluto for Arabic Speakers

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