1. "Comp"
I've been cycling a looooong time, and I still have no idea what this word is meant to refer to. At one time I thought it was meant to refer to a frame with carbon fiber added to it, but....it's not. I'm beginning to think it is cycling's version of the word "postmodern," a word so semantically loaded and context-intensive that it has literally lost all meaning it may have once had.
Feel free to add your own, I know there are a ton of them.