/ Dictionary / Index H horse's mouth: Meaning and Definition of Find definitions for: horse''s mouth' Pronunciation: [key] — Informal. Informal. See(def. 20). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. horse show horse's neck Related Content Daily Word Quiz: longevity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language