Also, Styxian and Phrygian. (Not that long, I know, but neat nevertheless.) :o
Also, “falling out a window.” The first time I encountered this word was in one of the later books of Gore Vidal’s ***America ***series. I knew immediately what it meant from having studied both Latin and German.
How about *antebellum *for pre-CW America, antedeluvian for pre-Flood history, and *antipodean *with respect to Scott and Amundsen?
Can you say *antipastean *where dinner is concerned? :dubious: 
I learned this one because of the band back in the '80s.
“Monosyllabic” is possibly the most ironic word in the English language.
I think it ties with “Abbreviation”.
Googleplex, although you could never use it in RL.
Phonetic could be in there too.
Solids? Pshaw. I can out-dimension you with the example I was going to post anyway, “hyperparallelopiped”.
I like conjunctivodacryocystorhinostomy, a surgical procedure that sticks a glass tube between the corner of your eye and the inside of your nose. (That’s the longest word I’ve seen in the wild.) Honorable mention goes to eleemosynary for the funky Greek spelling/pronunciation combo.
Having recently re-read Pratchett, I’ll mention one of his favorites: susurration
He seemed to work it into many of his Discworld novels.
Try ferroequinology: the study of iron horses; i.e, locomotives
I’m partial to gruntled.
Did you mean Stygian?
Higher dimensionality does not equate with “better”
I have it on the authority of Mr. Square of Flatland.
I’m partial to discombobulated.
Yendred of the Planiverse agrees, as does Eck from The Outer Limits.
I’m sure it’s used commonly and I’ve even used it several times myself. But I suspect you mean “googolplex.” (And I’m sure I can come up with an example where it would make sense when discussing combinatorics, but it’d be pretty narrow and probably a bit contrived.) This is the Googleplex, by the way.
For, me, since learning it as a kid, and it’s an obvious one, is floccinaucinihilipilification. Now, granted, I may have used that word only once or twice in real life, tongue-in-cheek, with somebody who would be familiar with it (or otherwise enjoy its use), but it always gives me a smile.
Just beat me to it!
I use it when playing hangman with non-native speakers, it’s actually much easier to get than short words (like ‘sky’) because it has so many different letters.
Oh, and this.
Probably. But I think it’s cooler with an x. 
Defenestrate.
Several years ago I found out that as a child I presented papyrophagia. That manages to make “munching on the corners of paper” sound like it’s something terribly dangerous.