The Collaborative International Dictionary of English v.0.48:

Cedrene \Ce"drene\ (s[=e]"dr[=e]n), n. (Chem.)
   A rich aromatic oil, C15H24, extracted from oil of red
   cedar, and regarded as a polymeric terpene; also any one of a
   class of similar substances, as the essential oils of cloves,
   cubebs, juniper, etc., of which cedrene proper is the type.
   [Written also cedren.]
   [1913 Webster]