Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

Source : WordNet®

ungratefulness
     n : a lack of gratitude [syn: {ingratitude}] [ant: {gratitude}]