The Collaborative International Dictionary of English v.0.48:

Ungrateful \Un*grate"ful\, a.
   1. Not grateful; not thankful for favors; making no returns,
      or making ill return for kindness, attention, etc.;
      ingrateful. --South.
      [1913 Webster]

   2. Unpleasing; unacceptable; disagreeable; as, harsh sounds
      are ungrateful to the ear.
      [1913 Webster] -- Un*grate"ful*ly, adv. --
      Un*grate"ful*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ungratefulness
    n 1: a lack of gratitude [syn: ingratitude, ungratefulness]
         [ant: gratitude]