The Collaborative International Dictionary of English v.0.48:

Complaint \Com*plaint"\ (k[o^]m*pl[=a]nt"), n. [F. complainte.
   See Complain.]
   1. Expression of grief, regret, pain, censure, or resentment;
      lamentation; murmuring; accusation; fault-finding.
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            I poured out my complaint before him. --Ps. cxlii.
                                                  2.
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            Grievous complaints of you.           --Shak.
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   2. Cause or subject of complaint or murmuring.
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            The poverty of the clergy in England hath been the
            complaint of all who wish well to the church.
                                                  --Swift.
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   3. An ailment or disease of the body.
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            One in a complaint of his bowels.     --Arbuthnot.
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   4. (Law) A formal allegation or charge against a party made
      or presented to the appropriate court or officer, as for a
      wrong done or a crime committed (in the latter case,
      generally under oath); an information; accusation; the
      initial bill in proceedings in equity.

   Syn: Lamentation; murmuring; sorrow; grief; disease; illness;
        disorder; malady; ailment.
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WordNet (r) 3.0 (2006):

complaint
    n 1: an often persistent bodily disorder or disease; a cause for
         complaining [syn: ailment, complaint, ill]
    2: (formerly) a loud cry (or repeated cries) of pain or rage or
       sorrow
    3: an expression of grievance or resentment
    4: (civil law) the first pleading of the plaintiff setting out
       the facts on which the claim for relief is based
    5: (criminal law) a pleading describing some wrong or offense;
       "he was arrested on a charge of larceny" [syn: charge,
       complaint]