euthiochroic, a. [Gr. e'y^ well + sulphur + color.].
Pertaining to, or denoting, an acid so called. [1913 Webster]
Euthiochroic acid (Chem.), a complex derivative of hydroquinone and sulphonic (thionic) acid. -- so called because it contains sulphur, and forms brilliantly colored (yellow) salts.