Source : Webster's Revised Unabridged Dictionary (1913)

Unsymmetrical \Un`sym*met"ric*al\, a.
   1. Wanting in symmetry, or due proportion pf parts.

   2. (Biol.) Not symmetrical; being without symmetry, as the
      parts of a flower when similar parts are of different size
      and shape, or when the parts of successive circles differ
      in number. See {Symmetry}.

   3. (Chem.) Being without symmetry of chemical structure or
      relation; as, an unsymmetrical carbon atom.

   {Unsymmetrical carbon atom} (Chem.), one which is united at
      once to four different atoms or radicals. This condition
      usually occasions physical isomerism, with the attendant
      action on polarized light.

Source : WordNet®

unsymmetrical
     adj 1: lacking symmetry [syn: {unsymmetric}]
     2: having unsymmetrical parts or unequal dimensions or
        measurements [syn: {anisometric}]