Source : Webster's Revised Unabridged Dictionary (1913)

Outsider \Out`sid"er\, n.
   1. One not belonging to the concern, institution, party,
      etc., spoken of; one disconnected in interest or feeling.
      [Recent] --A. Trollope.

   2. A locksmith's pinchers for grasping the point of a key in
      the keyhole, to open a door from the outside when the key
      is inside.

   3. A horse which is not a favorite in the betting. [Cant]

Source : WordNet®

outsider
     n 1: someone who is excluded from or is not a member of a group
          [syn: {foreigner}]
     2: a constestant (human or animal) not considered to have a
        good chance to win