The Collaborative International Dictionary of English v.0.48:

Nitric \Ni"tric\, a. [Cf. F. nitrique. See Niter.] (Chem.)
   Of, pertaining to, or containing, nitrogen; specifically,
   designating any one of those compounds in which, as
   contrasted with nitrous compounds, the element has a higher
   valence; as, nitric oxide; nitric acid.
   [1913 Webster]

   Nitric acid, a colorless or yellowish liquid obtained by
      distilling a nitrate with sulphuric acid. It is powerfully
      corrosive, being a strong acid, and in decomposition a
      strong oxidizer.

   Nitric anhydride, a white crystalline oxide of nitrogen
      (N2O5), called nitric pentoxide, and regarded as the
      anhydride of nitric acid.

   Nitric oxide, a colorless poisous gas (NO) obtained by
      treating nitric acid with copper. On contact with the air
      or with oxygen, it becomes reddish brown from the
      formation of nitrogen dioxide (NO2, also called nitric
      dioxide or nitric peroxide).
      [1913 Webster]

WordNet (r) 3.0 (2006):

nitric oxide
    n 1: a poisonous red-brown gas (NO)