The Collaborative International Dictionary of English v.0.48:

Complain \Com*plain"\ (k[o^]m*pl[=a]n"), v. i. [imp. & p. p.
   Complained (k[o^]m*pl[=a]nd"); 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.
      [1913 Webster]

            O loss of sight, of thee I most complain! --Milton.
      [1913 Webster]

   2. To make a formal accusation; to make a charge.
      [1913 Webster]

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

   Syn: To repine; grumble; deplore; bewail; grieve; mourn;
        regret; murmur.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Complain \Com*plain"\, v. t.
   To lament; to bewail. [Obs.]
   [1913 Webster]

         They might the grievance inwardly complain. --Daniel.
   [1913 Webster]

         By chaste Lucrece's soul that late complain'd
         Her wrongs to us.                        --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

complain
    v 1: express complaints, discontent, displeasure, or
         unhappiness; "My mother complains all day"; "She has a lot
         to kick about" [syn: complain, kick, plain, sound
         off, quetch, kvetch] [ant: cheer, cheer up, chirk
         up]
    2: make a formal accusation; bring a formal charge; "The
       plaintiff's lawyer complained that he defendant had
       physically abused his client"

Moby Thesaurus II by Grady Ward, 1.0:

132 Moby Thesaurus words for "complain":
   accuse, ail, air a grievance, allege, arraign, article,
   be affected with, beef, bellyache, bemoan, bitch, boggle, book,
   boycott, bring accusation, bring charges, bring to book,
   call in question, carp at, challenge, charge, cite, clamor,
   complain loudly, complain of, confront, contend with, crab, croak,
   cry, cry out against, demonstrate, demonstrate against, demur,
   denounce, denunciate, dispute, dissent, enter a protest,
   expostulate, face down, face out, face up to, fasten on,
   fasten upon, feel ill, find fault, finger, fret, fret and fume,
   front, fuss, gripe, groan, grouch, grouse, growl, grumble, grunt,
   hang something on, holler, howl, impeach, imply, impute, indict,
   inform against, inform on, insinuate, kick, kick against,
   labor under, lament, lay charges, lodge a complaint,
   lodge a plaint, make a stand, march, meet head-on, moan, murmur,
   mutter, nag, object, offer resistance, oppose, pester, picket,
   pin on, prefer charges, press charges, press objections, protest,
   put on report, raise a howl, rally, recalcitrate,
   register a complaint, reluct, remonstrate, repine, report,
   reproach, revolt, scruple, show fight, sing the blues, sit in,
   squawk, stand, stand at bay, stand up against, stand up to,
   state a grievance, strike, strive against, suffer, take on,
   take to task, task, taunt with, tax, teach in, twit, wail, whimper,
   whine, withstand, worry, yap, yell bloody murder, yelp