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.
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.
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.
Grenville seized the opportunity to declaim on the
repeal of the stamp act. --Bancroft.