just out of curiosity, why do you want to know?
I have done some fairly extensive reading of 18.33 and cannot say that I have seen such a reference to "loaded" either. Maybe I'll look again and see if I glossed over it. As my own personal rule of thumb, a gun is "loaded" even with only 1 round in it, whether it be in the magazine or in the chamber/cylinder as the case may be. If there is a live round in the gun itself, I consider it loaded.
Most importantly don't forget, even when unloaded, all guns are loaded ALL THE TIME.