The Collaborative International Dictionary of English v.0.48:

Declaim \De*claim"\, v. t.
   1. To utter in public; to deliver in a rhetorical or set
      manner.
      [1913 Webster]

   2. To defend by declamation; to advocate loudly. [Obs.]
      "Declaims his cause." --South.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Declaim \De*claim"\ (d[-e]*kl[=a]m"), v. i. [imp. & p. p.
   Declaimed (d[-e]*kl[=a]md"); p. pr. & vb. n. Declaiming.]
   [L. declamare; de- + clamare to cry out: cf. F. d['e]clamer.
   See Claim.]
   1. To speak rhetorically; to make a formal speech or oration;
      to harangue; specifically, to recite a speech, poem, etc.,
      in public as a rhetorical exercise; to practice public
      speaking; as, the students declaim twice a week.
      [1913 Webster]

   2. To speak for rhetorical display; to speak pompously,
      noisily, or theatrically; to make an empty speech; to
      rehearse trite arguments in debate; to rant.
      [1913 Webster]

            Grenville seized the opportunity to declaim on the
            repeal of the stamp act.              --Bancroft.
      [1913 Webster]

WordNet (r) 3.0 (2006):

declaim
    v 1: recite in elocution [syn: declaim, recite]
    2: speak against in an impassioned manner; "he declaimed against
       the wasteful ways of modern society" [syn: declaim,
       inveigh]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "declaim":
   blare, blare forth, blaze, blaze abroad, blazon, blazon about,
   celebrate, chatter, converse, cry, cry out, debate, demagogue,
   elocute, gab, grimace, ham, ham it up, harangue, herald,
   herald abroad, hold forth, mouth, mug, orate, out-herod Herod,
   overact, overdramatize, patter, perorate, proclaim, promulgate,
   rabble-rouse, rant, rave, read, recite, roar, rodomontade, shout,
   soapbox, speak, spiel, spout, talk, throw away, thunder,
   thunder forth, trumpet, trumpet forth, tub-thump, underact,
   wag the tongue