The Collaborative International Dictionary of English v.0.48:

Xanthoxylene \Xan*thox"y*lene\, n. [See Xanthoxylum.] (Chem.)
   A liquid hydrocarbon of the terpene series extracted from the
   seeds of a Japanese prickly ash (Xanthoxylum pipertium) as
   an aromatic oil.
   [1913 Webster]