Well, this is not a “big” word, but it is one that is often misused: Surreal.
It came to mind because I have a current professor in a Script Analysis class, who politely challenged my use of it recently when I described a script we were using as, among other things, “surreal”.
Seems it is a pet peeve of hers, the way it gets tossed around, as in “Dude, that was so SURREAL!” 
I told her I was fairly sure I was using it appropriately, as I meant to indicate what it MEANT, she suggested I look it up, and next class, armed with official definitions, I proved my case. ( I suspect she was using me/my mention as a “teaching moment” for the class, since she readily conceded the point and is still giving me A’s)
As a Film Major, yes, I KNOW the origin of the word and what “surrealism” is in art/film, philosophy. And I’m 44 and fairly well read.
I ALSO know it means, “having a dreamlike or otherworldly quality”, and the play we were discussing DID, imo. (Eurydice, by Sarah Ruhl). Deals with the Underworld and death, has talking stones, impossible situations, and a raining elevator and even the author states the setting should be more like “Alice in Wonderland” than the Underworld as conventionally considered. :rolleyes:
But I have to agree with her that there are many words that younger (esp) people THINK they know but really don’t. Perhaps that is a whole 'nother topic, though.
I find that even in college, a great many younger students are woefully illiterate.
And I won’t even go INTO some of the people on Judge Judy 
Reminds me of the old SNL skit of the guy in prison who used all these big words, completely erroneously (oh, there’s one I guess half my classmates at any given time would not know off the top of their heads) 
But I am proud to say that MY 18 yr. old son probably knows more such words than I do…he’s odd that way. Has a thing for reading and obscure words and kicks much ass at Balderdash. 
“I do not think that word means what you think it means.” The Princess Bride