1. C₆H₅OH White, poisonous, corrosive crystals with sharp, burning taste; melts at 43_C, boils at 182_C; soluble in alcohol, water, ether, carbon disulfide, and other solvents; used to make resins and weed killers, and as a solvent and chemical intermediate. Also known as carbolic acid; phenylic acid. 2. A chemical compound based on the substitution product of phenol, for example, ethylphenol (C₂H₄C₄H₅OH), the ethyl substitute of phenol.