Orthogonal: The first time I heard the term, I thought it meant something like “11-sided.” It doesn’t. I’ve read the definition many times. I still don’t really get it, which didn’t stop me from casually dropping it into conversations with engineers.
Heh. I’ve had the same issue. Just in case you’re wondering it means, “Relating to or composed of right angles.”
Another word I can never remember… inchoate, “In an initial or early stage; incipient.”