I'm a Thoughtworks Alumnus

I left my position at Thoughtworks a couple of weeks ago to start working as an independent consultant. (So if you're interested in working with me then please get in touch!) Apparently this makes me a "Thoughtworks Alumnus", which I find rather odd. If I have "graduated" from Thoughtworks then what does that make my ex-colleagues that are still working there? Who are the students and who are the teachers..?