Definition of "Chapter"

[SydneyK]

Originally Posted by FΔithHΩpeLoΛe

Oh ok, I see - but not all organisations follow that system, right?

Right. Some organizations designate chapter name using other methods. Some fraternities, for example, designate the state where the chapter resides (Tennessee Beta, for example).

Originally Posted by FΔithHΩpeLoΛe

If I was starting a new Sorority could I just randomly pick three Greek letters based solely on the fact that a Sorority does not exist with that name? Especially if it's the founding chapter?

Correct. Only the founders choose the name of the sorority. And as Psi U MC Vito said, the name wouldn't be random letters - there's usually a reason why the chosen letters were chosen.

Originally Posted by FΔithHΩpeLoΛe

And Sydney: No, I'm not a member of any Sorority, I'm still trying to understand the system before I weigh up any options.

While that's noble and all, it isn't necessary to understand all the intricacies of Greek life before becoming active in Greek life. That's partly what the new member period is for. It sounds like you're wanting to start a new sorority - there are several threads on GC that you should read if you're really thinking about starting one.

ETA: Looks like several of us cross-posted, saying essentially the same things!