Often you'll see someone write a "Pompous Ass Word" online. I'd really like to have a word on hand that has the meaning "A word you don't know so you have to look it up", or something to that effect. So when someone else reads it and googles it, they hopefully have a little smack of self-awareness.
Example uses would be some sort of parody of their writing, or something like "Must you use a [...] just to sound smart?"
sesquipedalian [Oxford Online]
1(of a word) polysyllabic; long:
‘sesquipedalian surnames’
1.1 Characterized by long words; long-winded:
‘the sesquipedalian prose of scientific journals’
Here's a previous answer for "ten-dollar word"
You can also use the verb form, and say "Must you obfuscate?", but that applies to the entire thing the other person has said, not just the one obscure/pedantic/etc word.
pretentious (but everybody knows what pretentious means)ostentatious portentous I hope these help, and you could put them into an on line Thesaurus to get more ideas.
