The Collaborative International Dictionary of English v.0.48:

Thymol \Thym"ol\, n. [Thyme + -ol.] (Chem.)
   A phenol derivative of cymene, C10H13.OH, isomeric with
   carvacrol, found in oil of thyme, and extracted as a white
   crystalline substance of a pleasant aromatic odor and strong
   antiseptic properties; -- called also hydroxy cymene.
   [1913 Webster]