Definition of Simulation Single-Threading?

[pdspinelli]

I was wondering exactly how the CPU(s) is/are utilized by Fusion 360 in regards to both simulating/FEA and rendering models. According to Autodesk support, "Fusion 360 does not utilize all of the CPU and cores when solving local simulations. Most Fusion 360 simulation options are single-threaded, with limited control as to the utilization of the CPU during the solve." What exactly does it mean by single-threaded in this case? Does it mean a single thread in the entire computer, a single thread of each core, a single thread of a single core of a single CPU, a single thread of a single core in multiple CPU's if your architecture supports that, etc.? Maybe I just don't know what I'm talking about, but any insight would be greatly appreciated!!