The Collaborative International Dictionary of English v.0.48:

Productive \Pro*duc"tive\, a. [F. productif, L. productivus fit
   for prolongation.]
   [1913 Webster]
   1. Having the quality or power of producing; yielding or
      furnishing results; as, productive soil; productive
      enterprises; productive labor, that which increases the
      number or amount of products.
      [1913 Webster]

   2. Bringing into being; causing to exist; producing;
      originative; as, an age productive of great men; a spirit
      productive of heroic achievements.
      [1913 Webster]

            And kindle with thy own productive fire. --Dryden.
      [1913 Webster]

            This is turning nobility into a principle of virtue,
            and making it productive of merit.    --Spectator.
      [1913 Webster]

   3. Producing, or able to produce, in large measure; fertile;
      profitable.
      [1913 Webster] -- Pro*duc"tive*ly, adv. --
      Pro*duc"tive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

productively
    adv 1: in a productive way; "they worked together productively
           for two years" [syn: productively, fruitfully,
           profitably] [ant: fruitlessly, unproductively,
           unprofitably]