\Harts"horn`\, n. 1. The horn or antler of the hart, or male red deer. 2. Spirits of hartshorn (see below); volatile salts. {Hartshorn plantain} (Bot.), an annual species of plantain ({Plantago Coronopus}); -- called also {duck's-horn}. --Booth. {Hartshorn shavings}, originally taken from the horns of harts, are now obtained chiefly by planing down the bones of calves. They afford a kind of jelly. --Hebert. {Salt of hartshorn} (Chem.), an impure solid carbonate of ammonia, obtained by the destructive distillation of hartshorn, or any kind of bone; volatile salts. --Brande & C. {Spirits of hartshorn} (Chem.), a solution of ammonia in water; -- so called because formerly obtained from hartshorn shavings by destructive distillation. Similar ammoniacal solutions from other sources have received the same name.