Definition of "Complaint" :

noun: (criminal law) a pleading describing some wrong or offense

noun: (civil law) the first pleading of the plaintiff setting out the facts on which the claim for relief is based

noun: an expression of grievance or resentment

noun: (formerly) a loud cry (or repeated cries) of pain or rage or sorrow

noun: an often persistent bodily disorder or disease; a cause for complaining