Source : Webster's Revised Unabridged Dictionary (1913)

Coactive \Co*ac"tive\, a. [In sense 1, fr. 1st {Coact}; in sense
   2, fr. 2d {Coact}.]
   1. Serving to compel or constrain; compulsory; restrictive.

            Any coactive power or the civil kind. --Bp.
                                                  Warburton.

   2. Acting in concurrence; united in action.

            With what's unreal thou coactive art. --Shak.