Source : Webster's Revised Unabridged Dictionary (1913)

Xylostein \Xy*los"te*in\, n. [Xylo- + Gr. ? bone.] (Chem.)
   A glucoside found in the poisonous berries of a species of
   honeysuckle ({Lonicera xylosteum}), and extracted as a
   bitter, white, crystalline substance.