/ Dictionary / Index F fifth-wheel trailer: Meaning and Definition of Find definitions for: fifth'-wheel trail'er Pronunciation: (fifth'hwēl", -wēl" or, often, fith'-). [key] See under(def. 3). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fifth wheel fiftieth Related Content Daily Word Quiz: prevalent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language