The Collaborative International Dictionary
Indoxyl \In*dox"yl\, n. [Indigo + hydroxyl.] (Chem.) A nitrogenous substance, C8H7NO, isomeric with oxindol, obtained as an oily liquid.
Wiktionary
n. (context organic compound English) A hydroxyl derivative of indole produced by bacterial degradation of indoleacetic acid
Wikipedia
In chemistry, indoxyl is a nitrogenous substance with the chemical formula: CHNO. Indoxyl is isomeric with oxindol and is obtained as an oily liquid.
Indoxyl is obtained from indican, which is a glycoside. The hydrolysis of indican yields β-D- glucose and indoxyl.
Indigo dye is a product of the reaction of indoxyl by a mild oxidizing agent such as atmospheric oxygen.
Indoxyl can be found in urine and is titrated with Obermayer's reagent. Obermayer's reagent is a dilute solution FeCl3 in hydrochloric acid.