Source : Webster's Revised Unabridged Dictionary (1913)

Ammoniac \Am*mo"ni*ac\, Ammoniacal \Am`mo*ni"a*cal\, a.
   Of or pertaining to ammonia, or possessing its properties;
   as, an ammoniac salt; ammoniacal gas.

   {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}.

Ammoniac \Am*mo"ni*ac\(or Gum ammoniac \Gum` am*mo"ni*ac\, n.
   [L. Ammoniacum, Gr. ? 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 Persia 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 spirit of
   wine, and is used in medicine as an expectorant and
   resolvent, and for the formation of certain plasters.

Source : WordNet®

ammoniac
     n : the aromatic gum of the ammoniac plant [syn: {gum ammoniac}]

ammoniac
     adj : pertaining to or containing or similar to ammonia [syn: {ammoniacal}]