...and I've never understood what the difference in all these things are. They are mentioned in my states laws, but never defined. Our laws do define "knife" however. It has to have a blade 3-1/2" or longer. I don't know what they call something with a 2-1/2" blade. But I think all the definitions (or lack of them) are somewhat a moot point. There is a catch-all term in our laws, can't remember exactly what it is, something like "stabbing implement" (with no minimum length designation), that they could nail you with.