Naphthol

n. [ Naphthalene + -ol. ] (Chem.) Any one of a series of hydroxyl derivatives of naphthalene, analogous to phenol. In general they are crystalline substances with a phenol (carbolic) odor. [ 1913 Webster ]

Naphthol blue,
Naphthol orange,
Naphthol yellow (Chem.), brilliant dyestuffs produced from certain complex nitrogenous derivatives of naphthol or naphthoquinone. [ 1913 Webster ]