Source : Webster's Revised Unabridged Dictionary (1913)

Synergism \Syn"er*gism\, n. [See {Synergetic}.] (Theol.)
   The doctrine or theory, attributed to Melanchthon, that in
   the regeneration of a human soul there is a co["o]peration,
   or joint agency, on the part both of God and of man.

Source : WordNet®

synergism
     n 1: the working together of two things (muscles or drugs for
          example) to produce an effect greater than the sum of
          their individual effects [syn: {synergy}]
     2: the theological doctrine that salvation results from the
        interaction of human will and divine grace