/ Dictionary / Index B backflow valve: Meaning and Definition of Find definitions for: back'flow valve". Pronunciation: [key] See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. backflow back focus Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language