The Collaborative International Dictionary of English v.0.48:

Oxamic \Ox*am"ic\, a. [Oxalic + amido] (Chem.)
   Pertaining to, or designating, an acid NH2.CO.CO.HO
   obtained as a fine crystalline powder, intermediate between
   oxalic acid and oxamide. Its ammonium salt is obtained by
   boiling oxamide with ammonia.
   [1913 Webster]