Woof. I think Latin has changed since I was a kid. I doubted you; sorry 'bout that. In my youth, the Latin "bi" meant "two", while the Latin "semi" meant "half". Thus, bicycle or bisexual had to do with two, while hemisphere, demitasse and semiannual had to do with half. Oh, well. I was going to say "live and learn" there, but instead, live and what you've learned will change.