Source : Webster's Revised Unabridged Dictionary (1913)

Greatness \Great"ness\, n. [AS. gre['a]tnes.]
   1. The state, condition, or quality of being great; as,
      greatness of size, greatness of mind, power, etc.

   2. Pride; haughtiness. [Obs.]

            It is not of pride or greatness that he cometh not
            aboard your ships.                    --Bacon.

Source : WordNet®

greatness
     n 1: the property possessed by something or someone of
          outstanding importance
     2: unusual largeness in size or extent [syn: {enormousness}, {grandness},
         {immenseness}, {immensity}, {sizeableness}, {vastness}]