Grinder = crusher, weedmachine, herb- or hemp grinder, hackle or chopper.
It isn't important WHAT you call a grinder, because the grinder works best, even unnamed. You use a grinder to hackle herbs for the further handling. There are grinders in very different types and material, with two discs or more. And here are so many grinder designs. Well, there's just one thing left to say: happy grinding!