/ Dictionary / Index R rhombohedron: Meaning and Definition of Find definitions for: rhom•bo•he•dron Pronunciation: (rom"bu-hē'drun), [key] — pl. -drons, -dra a solid bounded by six rhombic planes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rhombohedron (Thesaurus) rhombic rhomboid Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language