noun
: a ammonium salt of carbonic acid: as
a. : the normal carbonate (NH 4 ) 2 CO 3 that readily decomposes into the bicarbonate and ammonia
b. : ammonium bicarbonate
c. : a white crystalline mixture of ammonium bicarbonate and ammonium carbamate obtained commercially by subliming an ammonium salt with calcium carbonate and used chiefly in medicine, in smalling salts, in baking powders, in fire-extinguishing compositions, and in scouring and dyeing preparations