The Collaborative International Dictionary of English v.0.48:

Bountiful \Boun"ti*ful\, a.
   [1913 Webster]
   1. Free in giving; liberal in bestowing gifts and favors.
      [1913 Webster]

            God, the bountiful Author of our being. --Locke.
      [1913 Webster]

   2. Plentiful; abundant; as, a bountiful supply of food.
      [1913 Webster]

   Syn: Liberal; munificent; generous; bounteous.
        [1913 Webster] -- Boun"ti*ful*ly, adv. --
        Boun"ti*ful*ness, n.
        [1913 Webster] Bountihead

WordNet (r) 3.0 (2006):

bountifulness
    n 1: the property of copious abundance [syn: amplitude,
         bountifulness, bounty]