*synergy*

n. [ Gr. &unr_;. 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 ]