The Collaborative International Dictionary of English v.0.48:

Wasteful \Waste"ful\, a.
   1. Full of waste; destructive to property; ruinous; as,
      wasteful practices or negligence; wasteful expenses.
      [1913 Webster]

   2. Expending, or tending to expend, property, or that which
      is valuable, in a needless or useless manner; lavish;
      prodigal; as, a wasteful person; a wasteful disposition.
      [1913 Webster]

   3. Waste; desolate; unoccupied; untilled. [Obs.]
      [1913 Webster]

            In wilderness and wasteful desert strayed.
                                                  --Spenser.
      [1913 Webster]

   Syn: Lavish; profuse; prodigal; extravagant.
        [1913 Webster] -- Waste"ful*ly, adv. --
        Waste"ful*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

wastefully
    adv 1: to a wasteful manner or to a wasteful degree; "we are
           still prodigally rich compared to others" [syn:
           wastefully, prodigally]