You already have an entry about the word "misled" being misunderstood as a verb - to misle. I am so glad I am not the only one - for years I saw, read and pronounced the word misled as though it rhymed with 'rise'. It made perfect sense to me as a word that was something like 'weaseled'. Noone ever corrected me, but somehow I finally figured it out on my own - several years after graduating from college with both Bachelor's and Master's degrees (and one of those with a minor in English)!
A childhood belief about speaking

others believed things like this
- In first grade, I thought that if I've never heard of a word before, then it wasn't a word.— Destiny
- When I was young I used to think that WHSmith was all one word, and was thus pronounced "Wwwhhhhuuusmith"— Nathan
- I used to believe that the word 'circumstances' was pronounced 'circus dancers'.— Mel
- When i first saw the word "Czech" somewhere, i pronounced it "siz-ETCH" in my head — Pachisu
- I used to think the word fever was just another word for giraff— Marshall m
- For years I heard the word "pedophile" and thought it meant a pedicurist's tool.— Lauren