magniloquent
Using pompous speech; speaking with deliberately long or esoteric words.
There is no doubt that the ordinary reader would enjoy, and he certainly would profit much by, a revival of the classic work—if only he did not fall asleep over its magniloquent but perissological otiosity.
Where it comes from
From post-Classical Latin magniloquens (“talkative, verbose”).
Adapted from the Wiktionary entry magniloquent (CC BY-SA 4.0).