Thanks for your question! The interface names are actually part of the Hardware of the Router and as such is a pre-configured name that you cannot change. You will notice that different Routers will have different naming conventions depending on the size of the interface (Ethernet, FastEthernet, GigabitEthernet) and how many of that interface is available.
You may not be aware but you can change the description of the interface. Here is an example!
Interface FastEthernet 0
You can then use a command like "show interface description" to see the different descriptions you have configured.