or , n. [ L. Ammoniacum, Gr. 'ammoniako`n a resinous gum, said to distill from a tree near the temple of Jupiter Ammon; cf. F. ammoniac. See Ammonite. ] (Med.) The concrete juice (gum resin) of an umbelliferous plant, the Dorema ammoniacum. It is brought chiefly from Iran in the form of yellowish tears, which occur singly, or are aggregated into masses. It has a peculiar smell, and a nauseous, sweet taste, followed by a bitter one. It is inflammable, partially soluble in water and in alcohol, and is used in medicine as an expectorant and resolvent, and for the formation of certain plasters. [ 1913 Webster + AS ]

{ } a. Of, pertaining, or containing ammonia, or possessing its properties; as, an ammoniac salt; ammoniacal gas. [ 1913 Webster ]

Ammoniacal engine, an engine in which the vapor of ammonia is used as the motive force. --
Sal ammoniac [ L. sal ammoniacus ], the salt usually called chloride of ammonium, and formerly muriate of ammonia. [ 1913 Webster ]

. Any fermentation process by which ammonia is formed, as that by which urea is converted into ammonium carbonate when urine is exposed to the air. [ Webster 1913 Suppl. ]