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

WordNet (r) 3.0 (2006):

dynamic
    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]
    2: of or relating to dynamics
    3: (used of verbs (e.g. `to run') and participial adjectives
       (e.g. `running' in `running water')) expressing action rather
       than a state of being [syn: active, dynamic] [ant:
       stative]
    n 1: an efficient incentive; "they hoped it would act as a
         spiritual dynamic on all churches" [syn: moral force,
         dynamic]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "dynamic":
   activating, active, acute, adventuresome, adventurous, aggressive,
   alive, ambitious, animated, armipotent, authoritative, brisk,
   cogent, driving, dynamical, eager, effective, electric,
   electrodynamic, emphatic, energetic, energizing, enterprising,
   enthusiastic, forceful, forcible, full of pep, functioning,
   geodynamic, go-ahead, go-go, hearty, high-potency, high-powered,
   high-pressure, high-tension, hustling, impetuous, in force,
   in power, incisive, intense, irresistible, keen, kinematic,
   kinetic, live, lively, living, lusty, mettlesome, mighty,
   mighty in battle, operative, peppy, potent, powerful, prepotent,
   puissant, pushful, pushing, pushy, radiodynamic, red-blooded,
   robust, ruling, running, smacking, snappy, spanking, spirited,
   spry, strenuous, striking, strong, take-charge, take-over, telling,
   trenchant, up-and-coming, valid, vehement, venturesome, venturous,
   vibrant, vigorous, violent, vital, vitalizing, vivacious, vivid,
   working, zealous, zestful, zesty, zippy