What's a 5th generation fighter?

The F-22 and F-35 are the only fighters I’ve read about that are considered “5th generation” fighters. The F-22 has superior stealth, supercruise, supermaneuverability and superior avionics/sensor fusion as its main attributes. The F-35 boasts superior stealth and superior avionics/sensor fusion. Other fighters like the EF and Gripen are said to have advanced avionics and some degree of sensor fusion but don’t have the same stealthiness.

So my question is – can a fighter be truly considered “5th” generation if it does not have a stealthy design? And as a follow up question – Can countries realistically overtake the US lead in stealth technology by any combination of begging, borrowing, buying or stealing or will they always be a step behind?