The Collaborative International Dictionary of English v.0.48:

Indophenol \In`do*phe"nol\, n. [Indigo + phenol.] (Chem.)
   Any one of a series of artificial blue dyestuffs, resembling
   indigo in appearance, and obtained by the action of phenol on
   certain nitrogenous derivatives of quinone. Simple indophenol
   proper, the parent compound of the dye series, is a
   quinonimine derivative with the formula C12H9NO2.
   [1913 Webster +PJC]