/ Dictionary / Index B ballast pocket: Meaning and Definition of Find definitions for: bal'last pock"et Pronunciation: [key] — Railroads. Railroads. a depression that is formed beneath the ballast layer by penetration of ballast particles into the subgrade and that tends to collect moisture. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ballast line ballast resistor Related Content Daily Word Quiz: stringent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language