Source : Webster's Revised Unabridged Dictionary (1913)

Fraxin \Frax"in\, n. [From {Fraxinus}.] (Chem.)
   A colorless crystalline substance, regarded as a glucoside,
   and found in the bark of the ash ({Fraxinus}) and along with
   esculin in the bark of the horse-chestnut. It shows a
   delicate fluorescence in alkaline solutions; -- called also
   {paviin}.