Source : Webster's Revised Unabridged Dictionary (1913)

Synergetic \Syn`er*get"ic\, a. [Gr. ?, fr. ? to work together;
   sy`n with + 'e`rgon work.]
   Working together; co["o]perating; as, synergetic muscles.

Source : WordNet®

synergetic
     adj : working together; used especially of groups, as subsidiaries
           of a corporation, cooperating for an enhanced effect;
           "a synergistic effect" [syn: {synergistic}]