>I also do maintenance of an application that was originally developed in the States. 'Terminated employees' is used widely in the functional specs. In the employee form there is no 'Terminate employee' button. The termination is done by filling the 'End date' field. I think that 'Terminate Employee' is a legitimate option, you might also consider a 'Set End Date' button or 'End Date' field.

That's a good idea. So far I'm working this form in my mind and I liked the option Active/Inactive suggested by Howard, the end date should also be on the form.