The Collaborative International Dictionary of English v.0.48:

Volition \Vo*li"tion\, n. [F., fr. L. volo I will, velle to
   will, be willing. See Voluntary.]
   1. The act of willing or choosing; the act of forming a
      purpose; the exercise of the will.
      [1913 Webster]

            Volition is the actual exercise of the power the
            mind has to order the consideration of any idea, or
            the forbearing to consider it.        --Locke.
      [1913 Webster]

            Volition is an act of the mind, knowingly exerting
            that dominion it takes itself to have over any part
            of the man, by employing it in, or withholding it
            from, any particular action.          --Locke.
      [1913 Webster]

   2. The result of an act or exercise of choosing or willing; a
      state of choice.
      [1913 Webster]

   3. The power of willing or determining; will.
      [1913 Webster]

   Syn: Will; choice; preference; determination; purpose.

   Usage: Volition, Choice. Choice is the familiar, and
          volition the scientific, term for the same state of
          the will; viz., an "elective preference." When we have
          "made up our minds" (as we say) to a thing, i. e.,
          have a settled state of choice respecting it, that
          state is called an immanent volition; when we put
          forth any particular act of choice, that act is called
          an emanent, or executive, or imperative, volition.
          When an immanent, or settled state of, choice, is one
          which controls or governs a series of actions, we call
          that state a predominant volition; while we give the
          name of subordinate volitions to those particular acts
          of choice which carry into effect the object sought
          for by the governing or "predominant volition." See
          Will.
          [1913 Webster]

WordNet (r) 3.0 (2006):

volition
    n 1: the capability of conscious choice and decision and
         intention; "the exercise of their volition we construe as
         revolt"- George Meredith [syn: volition, will]
    2: the act of making a choice; "followed my father of my own
       volition" [syn: volition, willing]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "volition":
   alternativity, animus, appetence, appetency, appetite, choice,
   choosing, co-optation, co-option, command, conation, conatus,
   decision, desire, determination, discretion, disposition, election,
   fancy, first choice, free choice, free will, inclination,
   intention, liking, lust, mind, objective, option, passion, pick,
   pleasure, preference, preoption, resolution, selection,
   sexual desire, the pick, velleity, will, will power, wish