The interface uses ringbuffers for communication between the kernel and userspace. That's how I have always understood it at least, not sure if it's actually correct.
Userspace ring buffers.
It’s a ring buffer. Not sure what the u is. Micro?
userspace?
No, it is two ring buffers, with the kernel in between moving requests from one side to the other. My guess is that the name describes the shape.
I always assumed it's the verb uring[1], but that might well be wrong.