lexiphanic
One who uses bombastic or pretentious wording or language.
rare
So what can you possibly say about someone who has actually compiled a dictionary of long and unusual words? […] “But Mrs. Byrne,” I said, “don’t you feel your dictionary might just metagrobolise (mystify) the average man and, worse, turn the harageous rodomontades (bold braggarts) among us into linguacious lexiphanics (talkative snobs)?”
Where it comes from
From Lexiphan(es) + -ic, after a character in the works of Lucian. Coined by the Scottish satirist Archibald Campbell as Lexiphanick, Lexiphanic in 1767.
Adapted from the Wiktionary entry lexiphanic (CC BY-SA 4.0).