/ Dictionary / Index R rubiaceous: Meaning and Definition of Find definitions for: ru•bi•a•ceous Pronunciation: (r"bē-ā'shus), [key] — adj. belonging to the Rubiaceae, the madder family of plants. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rubescent Rubicon 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