The Collaborative International Dictionary of English v.0.48:

Motive \Mo"tive\, a.
   Causing motion; having power to move, or tending to move; as,
   a motive argument; motive power. "Motive faculty." --Bp.
   Wilkins.
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   Motive power (Mach.), a natural agent, as water, steam,
      wind, electricity, etc., used to impart motion to
      machinery; a motor; a mover.
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The Collaborative International Dictionary of English v.0.48:

Motive \Mo"tive\, n. [F. motif, LL. motivum, from motivus
   moving, fr. L. movere, motum, to move. See Move.]
   1. That which moves; a mover. [Obs.] --Shak.
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   2. That which incites to action; anything prompting or
      exciting to choise, or moving the will; cause; reason;
      inducement; object; motivation[2].
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            By motive, I mean the whole of that which moves,
            excites, or invites the mind to volition, whether
            that be one thing singly, or many things
            conjunctively.                        --J. Edwards.
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   3. (Mus.) The theme or subject; a leading phrase or passage
      which is reproduced and varied through the course of a
      comor a movement; a short figure, or melodic germ, out of
      which a whole movement is develpoed. See also Leading
      motive, under Leading. [Written also motivo.]
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   4. (Fine Arts) That which produces conception, invention, or
      creation in the mind of the artist in undertaking his
      subject; the guiding or controlling idea manifested in a
      work of art, or any part of one.
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   Syn: Incentive; incitement; inducement; reason; spur;
        stimulus; cause.

   Usage: Motive, Inducement, Reason. Motive is the word
          originally used in speaking of that which determines
          the choice. We call it an inducement when it is
          attractive in its nature. We call it a reason when it
          is more immediately addressed to the intellect in the
          form of argument.
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The Collaborative International Dictionary of English v.0.48:

Motive \Mo"tive\, v. t.
   To prompt or incite by a motive or motives; to move.
   [1913 Webster]

WordNet (r) 3.0 (2006):

motive
    adj 1: causing or able to cause motion; "a motive force";
           "motive power"; "motor energy" [syn: motive(a),
           motor]
    2: impelling to action; "it may well be that ethical language
       has primarily a motivative function"- Arthur Pap; "motive
       pleas"; "motivating arguments" [syn: motivative(a),
       motive(a), motivating]
    n 1: the psychological feature that arouses an organism to
         action toward a desired goal; the reason for the action;
         that which gives purpose and direction to behavior; "we did
         not understand his motivation"; "he acted with the best of
         motives" [syn: motivation, motive, need]
    2: a theme that is repeated or elaborated in a piece of music
       [syn: motif, motive]
    3: a design or figure that consists of recurring shapes or
       colors, as in architecture or decoration [syn: motif,
       motive]