Does a GPU have multiple processors, each of which is a vector processor?

In Appendix C of Computer Organization and Design, Fifth Edition: The Hardware/Software interface by David A. Patterson, John L. Hennessy

The modern GPU that we describe here is a highly parallel, highly multithreaded multiprocessor optimized for visual computing.

By "multiprocessor", does it mean that a GPU has multiple processors, on which multiple processes or threads can run in parallel?

Is a GPU not just a single processor (a single processor can't run multiple processes or threads in parallel but concurrently at best), although by name, a GPU is a graphical processing unit?

Is each processor in a GPU a vector processor (which is SIMD, and is a single processor which can't run multiple processes or threads in parallel?)?

Does a GPU achieve both SIMD and MIMD? Does each of its processors alone achieve SIMD? Does it achieve MIMD with its multiple processors?

Thanks.