The Collaborative International Dictionary of English v.0.48:

Skeleton \Skel"e*ton\, n. [NL., fr. Gr. ???? (sc. ???) a dried
   body, a mummy, fr. ???? dried up, parched, ???? to dry, dry
   up, parch.]
   1. (Anat.)
      (a) The bony and cartilaginous framework which supports
          the soft parts of a vertebrate animal.

   Note: [See Illust. of the Human Skeleton, in Appendix.]
      (b) The more or less firm or hardened framework of an
          invertebrate animal.
          [1913 Webster]

   Note: In a wider sense, the skeleton includes the whole
         connective-tissue framework with the integument and its
         appendages. See Endoskeleton, and Exoskeleton.
         [1913 Webster]

   2. Hence, figuratively:
      (a) A very thin or lean person.
      (b) The framework of anything; the principal parts that
          support the rest, but without the appendages.
          [1913 Webster]

                The great skeleton of the world.  --Sir M. Hale.
          [1913 Webster]
      (c) The heads and outline of a literary production,
          especially of a sermon.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Skeleton \Skel"e*ton\, a.
   Consisting of, or resembling, a skeleton; consisting merely
   of the framework or outlines; having only certain leading
   features of anything; as, a skeleton sermon; a skeleton
   crystal.
   [1913 Webster]

   Skeleton bill, a bill or draft made out in blank as to the
      amount or payee, but signed by the acceptor. [Eng.]

   Skeleton key, a key with nearly the whole substance of the
      web filed away, to adapt it to avoid the wards of a lock;
      a master key; -- used for opening locks to which it has
      not been especially fitted.

   Skeleton leaf, a leaf from which the pulpy part has been
      removed by chemical means, the fibrous part alone
      remaining.

   Skeleton proof, a proof of a print or engraving, with the
      inscription outlined in hair strokes only, such proofs
      being taken before the engraving is finished.

   Skeleton regiment, a regiment which has its complement of
      officers, but in which there are few enlisted men.

   Skeleton shrimp (Zool.), a small crustacean of the genus
      Caprella. See Illust. under Laemodipoda.
      [1913 Webster]

WordNet (r) 3.0 (2006):

skeleton
    n 1: something reduced to its minimal form; "the battalion was a
         mere skeleton of its former self"; "the bare skeleton of a
         novel"
    2: a scandal that is kept secret; "there must be a skeleton
       somewhere in that family's closet" [syn: skeleton,
       skeleton in the closet, skeleton in the cupboard]
    3: the hard structure (bones and cartilages) that provides a
       frame for the body of an animal [syn: skeletal system,
       skeleton, frame, systema skeletale]
    4: the internal supporting structure that gives an artifact its
       shape; "the building has a steel skeleton" [syn: skeleton,
       skeletal frame, frame, underframe]