There was a gag in yesterday’s How I Met Your Mother that Ted said “Chameleon” wrong because he only read it and never heard it. I can sympathize. I said “Omnipotent” wrong for years because I only read it. Also “Hyperbole”. That was another one.
Any words like that for you?
Facade. I pronounced it “fa-KADE” until I was corrected by a friend amid some laughing and gentle ribbing.
Hyperbole was another one.
And I pronounced the “X” in faux (FAWKZ).
My mom thought it was hilarious when I was a kid and described two objects as being “simill-yer”.
Segue.
Epitome. I’d heard the word said aloud, but never associated the written word with that pronunciation. I always read it as “epi-tome”. :rolleyes:
Disciple. I used to put the stress on the first syllable, rather than the second. I still think the ‘correct’ pronunciation sounds kind of odd.
Facetious was another one.
For quite a few years I thought there were two singers: the one named “Fiance” that I kept hearing about and the one named “Be-younce” that I kept reading about.
It as only when I noticed the accent over the “e” in print that I realized it would be pronounced Be-youn-cee, and then further realized that she was the one I kept (mis)hearing about.
I think I’d read “ennui” for a few years before hearing it properly.
There’s a reason for the cedilla (façade). 
I bet it won’t be more than a few minutes until somebody mentions “awry.”
I’m still not sure how to pronounce pedagogy.
When I was much younger:
annihilate – If you hadn’t heard it pronounced, would you ever imagine it was pronounced ann-I-'il-ate ?
Names:
l"Hopital
Maugham (as in Somerset)
Verbatim. Also hors d’oeuvre.
Chamois
Ennui (I thought it was pronounced en-you-eye, I thought on-wee was a french name spelled like Henri. I was making this mistake up until a year ago actually)
**Hyperbole **(10th grade English sorted me out there, though)
**Milquetoast **(seriously why is this not spelled milktoast?)
Also, on a similar note, for years I thought that the differently-pronounced versions of the word “separate” were spelled differently [verb (SEP-uh-rate) spelled “separate” and adjective (sep-uh-RIT) spelled “seperate”]. All because of a typo in a Babysitters Club book I read when I was 8.
That was like me and “segue”. I thought there were two different words that meant roughly the same thing: “segue” and “segway” (and this is long before the two-wheeled vehicle thing). My rational was that the was a word “segway” that some how came from “segment” and “way” while the other word meant the same thing but had different language origins.
So “segway” and “segue” were kind of like “hors d’oeuvre” and “antipasto”.
I always thought “disheveled” was pronounced “dis-hev-ld,” since “dis” is clearly a prefix.
Turns out my reasoning was not heveled.
I used to have a problem with the word “amiable” – I’d pronounce it “uh-MY-a-ble”.
I still have to make a significant conscious effort not to say “hyper-bole” despite now knowing better.
I used to mispronounce “bodice” when I was a kid. I thought it was pronounced “bo-deese”.
I used to read “infrared” as “in-frared”. My ex always read “atomic” as “atom-ic”.
Ex-PLEE-tive de-LEET-ed. Isn’t that more mellifluous than the “correct” way?
When I was a kid I had a problem with superior. Super-y oar.