I always preferred “Other”. I think it’s even more universally understandable than my 2nd pick, “General Discussion”, and also shorter. You’ll see other pop up many other places, e.g. multiple-choice surveys.
I’m not a big fan of “off topic”. At least on a place like Meta, our Uncategorized discussion is not off topic per se. We don’t condone off-topic discussion here: You’re only allowed to talk about your favourite dog breed if it is somehow connected to your use of Discourse. So our Uncategorized category is for all those other topics that don’t quite fit into any of our standard categories.