ice giants

Noun

ice giant (plural ice giants)

1. (Norse) A frost giant.
   • The drops became living by the power of him who had sent the wind ; and from them sprang Ymir, the ice-giant.1832, Francis Lieber, Edward Wigglesworth, Thomas Gamaliel Bradford, editors, Encyclopædia Americana; A Popular Dictionary of Arts, Sciences, Literature, History, Politics, and Biography, volume 9...
2. A giant planet composed mostly of astronomical ices (condensed forms of volatile compounds) including water, methane, oxygen, carbon, nitrogen, and sulfur, and smaller than a gas giant. (e.g. Neptune and Uranus)
   • The fifth planet was an unknown, an ice giant in a drunken skewed orbit that took it from just inside the Jovian's orbit almost out to the sixth planet's.1976, Larry Niven, “The House Divided”, in A World Out of Time, Holt Rinehart Winston, →ISBN, archived from the original on 03 Dec 2021, page 38

   Synonyms:

   ice giant planet, Neptunian planet