Source : Webster's Revised Unabridged Dictionary (1913)

Overwork \O`ver*work"\, v. t. [imp. & p. p. {Overworked}or
   {Overwrought}; p. pr. & vb. n. {Overworking}.]
   1. To work beyond the strength; to cause to labor too much or
      too long; to tire excessively; as, to overwork a horse.

   2. To fill too full of work; to crowd with labor.

            My days with toil are overwrought.    --Longfellow.

   3. To decorate all over.

Source : WordNet®

overworking
     n : the act working too much or too long; "he became ill from
         overwork" [syn: {overwork}]