Source : Webster's Revised Unabridged Dictionary (1913)

Overlabor \O`ver*la"bor\, v. t. [imp. & p. p. {Overlabored}; p.
   pr. & vb. n. {Overlaboring}.]
   1. To cause to labor excessively; to overwork. --Dryden.

   2. To labor upon excessively; to refine unduly.