Source : Webster's Revised Unabridged Dictionary (1913)

Overweight \O"ver*weight`\, n.
   1. Weight over and above what is required by law or custom.

   2. Superabundance of weight; preponderance.

Overweight \O"ver*weight"\, a.
   Overweighing; excessive. [Obs.] ``Of no overweight worth.''
   --Fuller.

Source : WordNet®

overweight
     adj : usually describes a large person who is fat but has a large
           frame to carry it [syn: {fleshy}, {heavy}]
     n : the property of excessive fatness [syn: {corpulence}, {stoutness},
          {adiposis}]