A grievance is a complaint or a feeling of being treated unfairly or facing an injustice. It is a concern or dissatisfaction with something that you believe is wrong or unjust. Full definition
Form A-20, Appeal of Grievance Committee (or Hearing Panel) Dismissal or Appeal of Classification of Arbitration Request (nar.realtor)
How you handle yourself when airing grievances with your partner will have a direct impact on how they treat you. (marriage.com)
The Players Union filed grievances against ownership following each offseason — respectively dubbed Collusion I, II, and III — and an arbitrator sided with the players in each case. (sbnation.com)