Source : Webster's Revised Unabridged Dictionary (1913)

Unworthy \Un*wor"thy\, a.
   Not worthy; wanting merit, value, or fitness; undeserving;
   worthless; unbecoming; -- often with of. -- {Un*wor"thi*ly},
   adv. -- {Un*wor"thi*ness}, n.

Source : WordNet®

unworthiness
     n : the quality of being bad by virtue of lacking merit or value
         [ant: {worthiness}]