Source : Webster's Revised Unabridged Dictionary (1913)

Plentiful \Plen"ti*ful\, a.
   1. Containing plenty; copious; abundant; ample; as, a
      plentiful harvest; a plentiful supply of water.

   2. Yielding abundance; prolific; fruitful.

            If it be a long winter, it is commonly a more
            plentiful year.                       --Bacon.

   3. Lavish; profuse; prodigal. [Obs.]

            He that is plentiful in expenses will hardly be
            preserved from                        --Bacon.
      -- {Plen"ti*ful*ly}, adv. -- {Plen"ti*ful*ness}, n.

Source : WordNet®

plentifulness
     n : a full supply; "there was plenty of food for everyone" [syn:
          {plenty}, {plenteousness}, {plenitude}, {plentitude}]