To oversimplify the term, say you have a stock GN and you decide you want a higher stall. You throw in a 4500 nonlockup. Now when you leave the stoplight with your engine reving higher to get the car moving since the torque output of the engine hasn't changed. That would be a loose converter. The stator vane angles, pump vane angles, internal spacing all have to do with how "loose" a converter is...along with how much torque your engine puts thru it.