Source : Webster's Revised Unabridged Dictionary (1913)

Stoutness \Stout"ness\, n.
   The state or quality of being stout.

   Syn: Strength; bulk; courage; force; valor; lustiness;
        brawniness; boldness; fortitude; stubbornness.

Source : WordNet®

stoutness
     n 1: the property of being strong and resolute [syn: {stalwartness}]
     2: the property of excessive fatness [syn: {corpulence}, {overweight},
         {adiposis}]