I don't know if I've had a real, definitive answer for this. I saw some things online about how it may be due to the fact that doctors thought it was on the borderline of schizophrenia. My neighbor swears it's because we don't have 'borders' or boundaries (which, btw, I don't agree with that blanket statement). I think that the term borderline confuses people and just makes things more complicated when the situation is complicated enough! So, does anyone have any idea why it's called 'borderline' personality disorder? I'd appreciate it.