Haha, BPD seems to be (scarily) such a complex condition with so many facets that it seems impossible to try to describe it all in just one sentence, or even in a brief paragraph. Consequently, I've attempted numerous times to challenge this notion by trying to summarize it all into one sentence or even a simple explanation. But to no avail - I can't ever seem to do it justice, haha.

Lol, my latest attempt is this: "A state of being where, basically, life eats you up alive".

Which, even the sound of that can be quite scary...

But I guess that could also kinda go with such things like severe depression and anxiety...

But hell, depression and anxiety are a couple of possibilities out of a handful of facets of BPD.

An attempt at a simple explanation I've came up with before was - (for a non-borderline individual) "Imagine your most stressful day ever, with a sense of turbulent, inner and outer emotional chaos - NOW, imagine living in that state for most, if not all the days of your life".

This condition is one HELL of an emotional and mental labyrinth. Not to sound cheesy, but it really does take its toll on its victims.