n (organic compound|uncountable) A caustic, poisonous, white crystalline compound, C6H5OH, derived from benzene and used in resins, plastics, and pharmaceuticals and in dilute form as a disinfectant and antiseptic; once called carbolic acid.
n (organic chemistry|countable) Any of a class of aromatic organic compounds having at least one hydroxyl group attached directly to the benzene ring.