Pluto

noun Plu·to \ ˈplü-(ˌ)tō \

Usage guide: Is pluto a planet?

Definition of Pluto

1 : the Greek god of the underworld — compare dis

[New Latin]

: a dwarf planet occupying an orbit that crosses the orbit of Neptune

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Is pluto a planet?

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.

Origin and Etymology of pluto

Latin Pluton-, Pluto, from Greek Ploutōn

NEW! Time Traveler

First Known Use: 14th century

in the meaning defined at sense 1

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PLUTO Defined for English Language Learners

Pluto

noun

Definition of Pluto for English Language Learners

: 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

PLUTO Defined for Kids

Pluto

noun Plu·to \ ˈplü-tō \

Definition of Pluto for Students

: 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