Naph·thol n.  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.
  Naphthol blue, Naphthol orange, Naphthol yellow Chem., brilliant dyestuffs produced from certain complex nitrogenous derivatives of naphthol or naphthoquinone.
  ◄ ►