The Collaborative International Dictionary of English v.0.48:

Neglectful \Neg*lect"ful\, a.
   Full of neglect; heedless; careless; negligent; inattentive;
   indifferent. --Pope.
   [1913 Webster]

         A cold and neglectful countenance.       --Locke.
   [1913 Webster]

         Though the Romans had no great genius for trade, yet
         they were not entirely neglectful of it. --Arbuthnot.
   [1913 Webster] -- Neg*lect"ful*ly, adv. --
   Neg*lect"ful*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

neglectfulness
    n 1: the trait of neglecting responsibilities and lacking
         concern [syn: negligence, neglect, neglectfulness]