Breadcrumb Home > Dictionary > Index B back vent: Meaning and Definition of Find definitions for: back' vent" Pronunciation: [key] (in plumbing) a vent situated on the sewer side of a trap. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. backup light back walkover ✖ Related Content Daily Word Quiz: prandial Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language