(1) A class of aromatic organic compounds in which one or more of the hydroxy groups are attached directly to the benzene ring. (2) A white crystalline material called carbolic acid with a flashpoint of 175ºF, an ignition temperature of 1319ºF, it is toxic by ingestion, inhalation, or skin absorption. See: Phenylic Acid, Benzophenol, Hydroxybenzene