The Collaborative International Dictionary of English v.0.48:

Discontentment \Dis`con*tent"ment\, n.
   The state of being discontented; uneasiness; inquietude.
   --Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

discontentment
    n 1: a longing for something better than the present situation
         [syn: discontentment, discontent, discontentedness]
         [ant: contentment]