/ Dictionary / Index H hartshorn: Meaning and Definition of Find definitions for: harts•horn Pronunciation: (härts'hôrn"), [key] — n. the antler of a hart, formerly used as a source of ammonia. ammonium carbonate. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Hartmann hart's-tongue Related Content Daily Word Quiz: lyceum Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language