Source : Webster's Revised Unabridged Dictionary (1913)

Paraxylene \Par`a*xy"lene\, n. (Chem.)
   A hydrocarbon of the aromatic series obtained as a colorless
   liquid by the distillation of camphor with zinc chloride. It
   is one of the three metamers of xylene. Cf. {Metamer}, and
   {Xylene}.