/ Dictionary / Index F firmament: Meaning and Definition of Find definitions for: fir•ma•ment Pronunciation: (fûr'mu-munt), [key] — n. the vault of heaven; sky. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: firmament (Thesaurus) firm firman Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language