GNU Collaborative International Dictionary of English

Found one definition

1.       
   Synergy (?), n. [Gr. . See Synergetic.]
   2. Combined action; especially (Med.), the combined healthy action of every organ of a particular system; as, “the digestive synergy”.
   
   [1913 Webster]
   
   
   2. An effect of the interaction of the actions of two agents such that the result of the combined action is greater than expected as a simple additive combination of the two agents acting separately; -- also called synergism..  Opposite to antagonism.
   
   [PJC]