borderline personality disorder

2. The Mystery of Borderline Personality Disorder

By John Cloud / Seattle

People with borderline personality disorder are some of psychology's hardest cases. Many commit suicide. But recent treatment advances are unlocking what was once a mystery illness

borderline Show phonetics
adjective
between two very different conditions, with the possibility of belonging to either one of them:
Only in borderline cases (= cases where students might succeed or fail) will pupils have an oral exam.
She was a borderline candidate.

borderline Show phonetics
noun [S]
something that separates two different qualities:
The borderline between friendship and intimacy is often hard to define.