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.
[1913 Webster]