/ Dictionary / Index R rheo-: Meaning and Definition of Find definitions for: rheo- Pronunciation: [key] a combining form meaning “flow,” “current,” “stream,” used in the formation of compound words:Cf. rheoscope. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rhenium rheobase Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language