The Collaborative International Dictionary of English v.0.48:

Emotion \E*mo"tion\, n. [L. emovere, emotum, to remove, shake,
   stir up; e out + movere to move: cf. F. ['e]motion. See
   Move, and cf. Emmove.]
   A moving of the mind or soul; excitement of the feelings,
   whether pleasing or painful; disturbance or agitation of mind
   caused by a specific exciting cause and manifested by some
   sensible effect on the body.
   [1913 Webster]

         How different the emotions between departure and
         return!                                  --W. Irving.
   [1913 Webster]

         Some vague emotion of delight.           --Tennyson.

   Syn: Feeling; agitation; tremor; trepidation; perturbation;
        passion; excitement.

   Usage: Emotion, Feeling, Agitation. Feeling is the
          weaker term, and may be of the body or the mind.
          Emotion is of the mind alone, being the excited action
          of some inward susceptibility or feeling; as, an
          emotion of pity, terror, etc. Agitation may be bodily
          or mental, and usually arises in the latter case from
          a vehement struggle between contending desires or
          emotions. See Passion. "Agitations have but one
          character, viz., that of violence; emotions vary with
          the objects that awaken them. There are emotions
          either of tenderness or anger, either gentle or
          strong, either painful or pleasing." --Crabb.
          [1913 Webster]

WordNet (r) 3.0 (2006):

emotion
    n 1: any strong feeling

The Devil's Dictionary (1881-1906):

EMOTION, n.  A prostrating disease caused by a determination of the
heart to the head.  It is sometimes accompanied by a copious discharge
of hydrated chloride of sodium from the eyes.