The Collaborative International Dictionary of English v.0.48:

Dynamic \Dy*nam"ic\, Dynamical \Dy*nam"ic*al\, a. [Gr. ?
   powerful, fr. ? power, fr. ? to be able; cf. L. durus hard,
   E. dure: cf. F. dynamique.]
   1. Of or pertaining to dynamics; belonging to energy or
      power; characterized by energy or production of force.
      [1913 Webster]

            Science, as well as history, has its past to show,
            -- a past indeed, much larger; but its immensity is
            dynamic, not divine.                  --J.
                                                  Martineau.
      [1913 Webster]

            The vowel is produced by phonetic, not by dynamic,
            causes.                               --J. Peile.
      [1913 Webster]

   2. Relating to physical forces, effects, or laws; as,
      dynamical geology.
      [1913 Webster]

            As natural science has become more dynamic, so has
            history.                              --Prof. Shedd.
      [1913 Webster]

   Dynamical electricity. See under Electricity.
      [1913 Webster]

   Note: WordNet lists a number of narrower terms for dynamic
         and

The Collaborative International Dictionary of English v.0.48:

dynamical \dynamical\ adj. [Narrower terms: can-do; driving;
   energizing, energising, kinetic; forceful, slashing,
   vigorous; projectile; propellant, propellent, propelling,
   propulsive; renascent, resurgent; self-propelled,
   self-propelling; high-octane, high-powered, high-power,
   high-voltage]
   [WordNet 1.5] Dynamically \Dy*nam"ic*al*ly\, adv.
   In accordance with the principles of dynamics or moving
   forces. --J. Peile.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dynamical
    adj 1: characterized by action or forcefulness or force of
           personality; "a dynamic market"; "a dynamic speaker";
           "the dynamic president of the firm" [syn: dynamic,
           dynamical] [ant: adynamic, undynamic]