We don't have synonyms for ice giant yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are ice plant.
(n) :
(astronomy) 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)
(n) :
(astronomy) 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)