/ Thesaurus / C Synonyms of celestial sphere Find synonyms for: Noun1. celestial sphere, sphere, empyrean, firmament, heavens, vault of heaven, welkin, surfaceusage: the apparent surface of the imaginary sphere on which celestial bodies appear to be projectedWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: mongrel Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language