Am·mo·ni·ac (or Gum am·mo·ni·ac, n.  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.

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