Declaim, v. t.
1. To utter in public; to deliver in a rhetorical or set manner.
2. To defend by declamation; to advocate loudly. [Obs.] "Declaims his cause." South.
1 other Webster entry under this spelling
Declaim, v. i. [imp. & p. p. Declaimed; p. pr. & vb. n. Declaiming.]
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.
Shades of meaning
Fernald has no entry of its own for declaim; he lists it under speak.
He lists it without comment; the entries above explain its neighbors.