/ Dictionary / Index H horse fly: Meaning and Definition of Find definitions for: horse' fly" Pronunciation: [key] any bloodsucking, usually large fly of the family Tabanidae, esp. of the genus Tabanus, a serious pest of horses, cattle, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: horsefly (Thesaurus) horseflesh horse gentian Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language