The Collaborative International Dictionary of English v.0.48:

Dynamist \Dy"na*mist\, n.
   One who accounts for material phenomena by a theory of
   dynamics.
   [1913 Webster]

         Those who would resolve matter into centers of force
         may be said to constitute the school of dynamists.
                                                  --Ward (Dyn.
                                                  Sociol. ).
   [1913 Webster]