The Collaborative International Dictionary of English v.0.48:

Dynamism \Dy"na*mism\, n. [Cf. F. dynamisme. See Dynamics.]
   The doctrine of Leibnitz, that all substance involves force.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dynamism
    n 1: any of the various theories or doctrines or philosophical
         systems that attempt to explain the phenomena of the
         universe in terms of some immanent force or energy
    2: active strength of body or mind [syn: vigor, vigour,
       dynamism, heartiness]
    3: the activeness of an energetic personality [syn: dynamism,
       pizzazz, pizzaz, oomph, zing]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "dynamism":
   adventuresomeness, adventurousness, aggression, aggressiveness,
   ambitiousness, demonic energy, drive, energy, enterprise,
   enterprisingness, ergal, force, forcefulness, get-up-and-get,
   get-up-and-go, getup, go, go-ahead, go-getting, go-to-itiveness,
   gumption, hustle, initiative, intensity, kinetic energy,
   liveliness, pep, potency, potential energy, power, push,
   pushfulness, pushiness, pushingness, spirit, spiritedness, spunk,
   strength, strenuousness, up-and-comingness, venturesomeness,
   venturousness, vigor, vitality, zip