Sandit[i]on

[ryner]

I think I'm a fairly observant person, and I know I'm a bit neurotic when it comes to spelling and grammar, so it surprised me yesterday when I learned that the Jane Austen novel Sanditon is spelled exactly like that -- not Sandition. I've never read the book, but I've been aware of it as one of her works for probably close to two decades, and all this time I thought it was called Sandition. A quick search on Google suggests that I'm not the only one.

I wonder what other sorts of things are out there that I feel confident in my knowledge of but am actually mistaken?