/ Dictionary / Index P piggyback car: Meaning and Definition of Find definitions for: pig'gyback car" Pronunciation: [key] — Railroads. Railroads. a flatcar designed to accommodate containers or highway truck trailers. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. piggyback piggyback plant Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language