# STM32F103C8T6 5V pin description

On the STM32F103C8T6 there is a 5V pin, see at the bottom left of the STM:

However, in the official description from ST.com (see Link), in the table on page 28 is shown:

C2 F2 - - - 10 - VSS_5 S - VSS_5 - -

Which means the VSS 5V pin is a Supply pin. However, does this mean I can power the STM with a (USB) power adapter and connect the 5V power to this pin, or is it only for powering components connected to the STM with 5V?

Note, there are also VSS_4, VSS_3, VSS_2 and VSS_1 pins, so I'm even wondering if the VSS_5 pin is 5V, and which pin maps with with +5V on the picture.

The 5V pin you mention is pin 3 of the header P4, connected to a net called 5v. There is then a regulator to bring the 5 V down to 3.3 V on the VCC3V3 net which is used for powering the processor, so yes, you can connect 5 V there, or use the USB socket to power the processor. The pin labelled 5V and the USB power pin are shorted together, so you should only drive one of them.
The schematic seems to use VCC3v3 and VCC3V3 interchangeably, and the same with 5v and 5V, I'm assuming they're the same nets, else the regulator is redundant.