The Collaborative International Dictionary of English v.0.48:

Phenol \Phe"nol\ (f[=e]"n[=o]l; 277), n. [Gr. fai`nein to show +
   -ol: cf. F. ph['e]nol.] (Chem.)
   1. A white or pinkish crystalline substance, C6H5OH,
      produced by the destructive distillation of many organic
      bodies, as wood, coal, etc., and obtained from the heavy
      oil from coal tar.
      [1913 Webster]

   Note: It has a peculiar odor, somewhat resembling creosote,
         which is a complex mixture of phenol derivatives. It is
         of the type of alcohols, and is called also phenyl
         alcohol, but has acid properties, and hence is
         popularly called carbolic acid, and was formerly
         called phenic acid. It is a powerful caustic poison,
         and in dilute solution has been used as an antiseptic.
         [1913 Webster]

   2. Any one of the series of hydroxyl derivatives of which
      phenol proper is the type.
      [1913 Webster]

   Glacial phenol (Chem.), pure crystallized phenol or
      carbolic acid.

   Phenol acid (Chem.), any one of a series of compounds which
      are at once a derivative of phenol and an organic acid;
      thus, salicylic acid is a phenol acid.

   Phenol alcohol (Chem.), any one of series of derivatives of
      phenol and carbinol which have the properties of both
      combined; thus, saligenin is a phenol alcohol.

   Phenol aldehyde (Chem.), any one of a series of compounds
      having both phenol and aldehyde properties.

   Phenol phthalein. See phenolphthalein.
      [1913 Webster]

WordNet (r) 3.0 (2006):

phenol
    n 1: any of a class of weakly acidic organic compounds; molecule
         contains one or more hydroxyl groups
    2: a toxic white soluble crystalline acidic derivative of
       benzene; used in manufacturing and as a disinfectant and
       antiseptic; poisonous if taken internally [syn: carbolic
       acid, phenol, hydroxybenzene, oxybenzene, phenylic
       acid]