1.  grievance(n = noun.feeling) grudge, score - a resentment strong enough to justify retaliation; "holding a grudge"; "settling a score"
is a kind of bitterness, gall, rancor, rancour, resentment

2.  grievance(n = noun.communication) - an allegation that something imposes an illegal obligation or denies some legal right or causes injustice;
is a kind of allegation

3.  grievance(n = noun.communication) - a complaint about a (real or imaginary) wrong that causes resentment and is grounds for action;
is a kind of complaint

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."

grievance, n. a real or fancied cause for complaint.

Etymology:
ME, = injury, f. OF grevance (as GRIEF)

N  evil, ill, harm, hurt, mischief, nuisance, machinations of the devil, Pandora's box, ills that flesh is heir to, blow, buffet, stroke, scratch, bruise, wound, gash, mutilation, mortal blow, wound, immedicabile vulnus, damage, loss, disadvantage, prejudice, drawback, disaster, accident, casualty, mishap, bad job, devil to pay, calamity, bale, catastrophe, tragedy, ruin, adversity, mental suffering, demon, (Evil spirit) bane, (cause of evil), badness, (Production of Evil), painfulness, evil doer, outrage, wrong, injury, foul play, bad turn, ill turn, disservice, spoliation, grievance, crying evil, disastrous, bad, awry, out of joint, disadvantageous, amis, wrong, ill, to one's cost, moving accidents by flood and field.

N  painfulness, trouble, care, trial, affliction, infliction, blow, stroke, burden, load, curse, bitter pill, bitter draught, waters of bitterness, annoyance, grievance, nuisance, vexation, mortification, sickener, bore, bother, pother, hot water, sea of troubles, hornet's nest, plague, pest, cancer, ulcer, sting, thorn, canker, scorpion, dagger, scourge, carking care, canker worm of care, mishap, misfortune, desagrement, esclandre, rub, source of irritation, source of annoyance, wound, open sore, sore subject, skeleton in the closet, thorn in the flesh, thorn in one's side, where the shoe pinches, gall and wormwood, sorry sight, heavy news, provocation, affront, head and front of one's offending, infestation, molestation, malignity, causing pain, hurting, hurtful, painful, dolorific, dolorous, unpleasant, unpleasing, displeasing, disagreeable, unpalatable, bitter, distasteful, uninviting, unwelcome, undesirable, undesired, obnoxious, unacceptable, unpopular, thankless, unsatisfactory, untoward, unlucky, uncomfortable, distressing, afflicting, afflictive, joyless, cheerless, comfortless, dismal, disheartening, depressing, depressive, dreary, melancholy, grievous, piteous, woeful, rueful, mournful, deplorable, pitiable, lamentable, sad, affecting, touching, pathetic, irritating, provoking, stinging, annoying, aggravating, mortifying, galling, unaccommodating, invidious, vexatious, troublesome, tiresome, irksome, wearisome, plaguing, plaguy, awkward, importunate, teasing, pestering, bothering, harassing, worrying, tormenting, carking, intolerable, insufferable, insupportable, unbearable, unendurable, past bearing, not to be borne, not to be endured, more than flesh and blood can bear, enough to drive one mad, enough to provoke a saint, enough to make a parson swear, enough to gag a maggot, shocking, terrific, grim, appalling, crushing, dreadful, fearful, frightful, thrilling, tremendous, dire, heart-breaking, heart-rending, heart-wounding, heart-corroding, heart-sickening, harrowing, rending, odious, hateful, execrable, repulsive, repellent, abhorrent, horrid, horrible, horrific, horrifying, offensive, nauseous, nauseating, disgusting, sickening, revolting, nasty, loathsome, loathful, fulsome, vile, hideous, sharp, acute, sore, severe, grave, hard, harsh, cruel, biting, caustic, cutting, corroding, consuming, racking, excruciating, searching, grinding, grating, agonizing, envenomed, catheretic, pyrotic, ruinous, disastrous, calamitous, tragical, desolating, withering, burdensome, onerous, oppressive, cumbrous, cumbersome, painfully, with pain, deuced, Int, hinc illae lachrymae!, surgit amari aliquid, the place being too hot to hold one, the iron entering into the soul, he jests at scars that never felt a wound, I must be cruel only to be kind, what deep wounds ever closed without a scar?.

N  wrong, what ought not to be, what should not be, malum in se, unreasonableness, grievance, shame, injustice, tort, unfairness, iniquity, foul play, partiality, leaning, bias, favor, favoritism, nepotism, party spirit, partisanship, bigotry, undueness, wrongdoing (vice), unlawfulness, robbing Peter to pay Paul, the wolf and the lamb, vice, a custom more honored in the breach than the obser, wrong, wrongful, bad, too bad, unjust, unfair, inequitable, unequitable, unequal, partial, one-sided, injurious, tortious, objectionable, unreasonable, unallowable, unwarrantable, unjustifiable, improper, unfit, unjustified, illegal, iniquitous, immoral, in the wrong, in the wrong box, wrongly, it will not do.