I was reading a rather interesting article in Soundcontrol magazine about magazine about Vibrato arms, from Bigby to Floyd Rose To EdgePro to Knife Edge systems, there was a lot covered there! It talked about the way people get the name of the device wrong in a technical sense, and even how manufacturers (Kahler, for instance) get the name wrong!
Interestingly, the guy who wrote the article was the head guitar technician for Sound Control in London, and over the years he had even heard people call them things like "Wah wah bars" and even the "Distrotion stick". I loved the distortion stick moniker so much I started calling them that in a joking way for a while!
Also, I'm pretty sure the name "whammy bar" was invented by surf guitarists, and stuck. Digitech's pedal is named after the whole thing, it mimics the effect of a Vibrato unit in a sense.
