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]