Source : Webster's Revised Unabridged Dictionary (1913)

Complain \Com*plain"\, v. i. [imp. & p. p. {Complained}; p. pr.
   & vb. n. {Complaining}.] [F. complaindre, LL. complangere;
   com- + L. plangere to strike, beat, to beat the breast or
   head as a sign of grief, to lament. See {Plaint}.]
   1. To give utterance to expression of grief, pain, censure,
      regret. etc.; to lament; to murmur; to find fault; --
      commonly used with of. Also, to creak or squeak, as a
      timber or wheel.

            O loss of sight, of thee I most complain! --Milton.

   2. To make a formal accusation; to make a charge.

            Now, Master Shallow, you'll complain of me to the
            king?                                 --Shak.

   Syn: To repine; grumble; deplore; bewail; grieve; mourn;
        regret; murmur.

Source : WordNet®

complaining
     adj : expressing pain or dissatisfaction of resentment; "a
           complaining wife" [syn: {complaining(a)}, {complaintive}]
           [ant: {uncomplaining}]