Saturnine, which I’m convinced means Byronically handsome. But when I look it up seems to just mean “dark” or “gloomy”.
Pusillanimous, which I’m always a hundred per cent certain means “stingy” but turns out to mean “cowardly”.
Chiaroscuro, which I have long confused with kaleidoscopic, but which actually means black and white. Or a kind of drawing in black and white. Or something. To be honest it’s a word I now avoid.
I know I’m not alone on this. What are yours?