/ Dictionary / Index H harmonium: Meaning and Definition of Find definitions for: har•mo•ni•um Pronunciation: (här-mō'nē-um), [key] — n. an organlike keyboard instrument with small metal reeds and a pair of bellows operated by the player's feet. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: harmonium (Thesaurus) harmonistic harmonize Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language