Source : Webster's Revised Unabridged Dictionary (1913)

Oxonic \Ox*on"ic\, a. [Prob. glyoxalic + carbonic.] (Chem.)
   Pertaining to, or designating, a complex nitrogenous acid
   ({C4H5N3O4}) not known in the free state, but obtained, in
   combination with its salts, by a slow oxidation of uric acid,
   to which it is related.