What is "euchroic"

Euchroic \Eu*chro"ic\, a. [Gr. ? well-colored; e'y^ well + ? color.] (Chem.) Having a fine color.

Euchroic acid (Chem.), an organic, imide acid, obtained as a colorless crystalline substance, C12H4N2O8 by heating an ammonium salt of mellitic acid. By reduction it is changed to a dark blue substance (euchrone), -- hence its name.