The Collaborative International Dictionary of English v.0.48:

Grievance \Griev"ance\, n. [OF. grevance. See Grieve, v. t.]
   1. A cause of uneasiness and complaint; a wrong done and
      suffered; that which gives ground for remonstrance or
      resistance, as arising from injustice, tyranny, etc.;
      injury.
      [1913 Webster]

   2. Grieving; grief; affliction.
      [1913 Webster]

            The . . . grievance of a mind unreasonably yoked.
                                                  --Milton.

   Syn: Burden; oppression; hardship; trouble.
        [1913 Webster]

WordNet (r) 3.0 (2006):

grievance
    n 1: a resentment strong enough to justify retaliation; "holding
         a grudge"; "settling a score" [syn: grudge, score,
         grievance]
    2: an allegation that something imposes an illegal obligation or
       denies some legal right or causes injustice
    3: a complaint about a (real or imaginary) wrong that causes
       resentment and is grounds for action

Moby Thesaurus II by Grady Ward, 1.0:

150 Moby Thesaurus words for "grievance":
   abomination, affliction, affront, allegation, atrocity, bad, bane,
   beef, beefing, befoulment, bellyache, bellyaching, bitch, bitching,
   bitter cup, bitter draft, bitter draught, bitter pill, blight,
   bone to pick, boycott, bugbear, burden, burden of care, calamity,
   cankerworm of care, care, challenge, charge, complaining,
   complaint, compunction, corruption, cross, crow to pluck,
   crown of thorns, crushing burden, crying evil, curse, damage,
   death, defilement, demonstration, demur, demurrer, despoliation,
   destruction, destructive criticism, detriment, disease, dissent,
   disservice, distress, encumbrance, evil, exception, expostulation,
   faultfinding, gall, gall and wormwood, great wrong,
   grievance committee, gripe, griping, groan, groaning,
   gross injustice, grouse, grousing, grudge, grumbling, hardship,
   harm, havoc, holler, howl, hurt, ill, imposition,
   indignation meeting, indignity, infection, infliction, injury,
   injustice, kick, kicking, load, march, miscarriage of justice,
   mischief, murmuring, nemesis, nonviolent protest, objection,
   open wound, oppression, outrage, pack of troubles,
   peck of troubles, peeve, peevishness, pest, pestilence, pet peeve,
   petulance, picketing, plague, plaint, poison, pollution, protest,
   protest demonstration, protestation, qualm, querulousness, rally,
   raw deal, remonstrance, remonstration, rigor, running sore,
   scolding, scourge, scruple, sea of troubles, sit-in, sniping,
   sorrow, squawk, squawking, strike, teach-in, the worst, thorn,
   torment, toxin, trial, tribulation, trouble, unfairness, venom,
   vexation, visitation, waters of bitterness, weight, whining, woe,
   wrong, yapping