/ Dictionary / Index T trial horse: Meaning and Definition of Find definitions for: tri'al horse" Pronunciation: [key] — Informal. Informal. an opponent who performs against a superior foe in a workout or exhibition. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. trial examiner trial jury Related Content Daily Word Quiz: fresco Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language