Source : Webster's Revised Unabridged Dictionary (1913)

Hormone \Hor"mone\ (h[^o]r"m[=o]n), n. [From Gr. "orma`ein to
   excite.] (Physiol. Chem.)
   A chemical substance formed in one organ and carried in the
   circulation to another organ on which it exerts a stimulating
   effect; thus, according to Starling, the gastric glands are
   stimulated by a hormone from the pyloric mucous membrane.

Source : WordNet®

hormone
     n : the secretion of an endocrine gland that is transmitted by
         the blood to the tissue on which it has a specific effect
         [syn: {endocrine}, {internal secretion}]