/ Dictionary / Index R river birch: Meaning and Definition of Find definitions for: riv'er birch" Pronunciation: [key] a tree, Betula nigra, of the eastern U.S., having papery, reddish-brown bark that peels away. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. riverbed river blindness 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