gas giant

[ gas-jahy-uhnt ]
/ ˈgæs ˌdʒaɪ ənt /

noun Astronomy.

a giant planet composed mostly of hydrogen and helium: the two gas giants in our solar system, Jupiter and Saturn, are sometimes called failed stars because their composition is similar to that of stars, but this is largely considered misleading, as gas giants, unlike brown dwarfs, do not form as stars do.

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Origin of gas giant

First recorded in 1950–55
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for gas giant

British Dictionary definitions for gas giant

gas giant

noun

one of the four planets in our solar system that are composed chiefly of hydrogen and helium, namely Jupiter, Saturn, Uranus, and Neptune

Word Origin for gas giant

C20: coined by James Blish (1921–75), US science fiction writer
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

Scientific definitions for gas giant

gas giant

A large, massive, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in either gaseous or liquid state. Gas giants have swirling atmospheres primarily of hydrogen and helium, with no well-defined planetary surface; they are assumed to have rocky cores. They are also characterized by ring systems, although only Saturn's is readily visible from Earth. Our solar system contains four gas giants: Jupiter, Saturn, Uranus, and Neptune. The majority of extrasolar planets discovered so far are the size of the solar system's gas giants, although they orbit their stars much more closely and may differ in composition from ours. Also called Jovian planet Compare terrestrial planet.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.