Personality Disorders Support Group
Personality disorders form a class of mental disorders that are characterized by long-lasting rigid patterns of thought and behaviour. Personality disorders are seen by the American Psychiatric Association as an enduring pattern of inner experience and behavior that deviates markedly from the expectations of the culture of the individual who exhibits it.

Random fact:
In early DSM versions it was called
'Unstable Personality Disorder'
&
At one point it was defined as "Bordering between psychotic and neurotic"
However, Borderlines can have Antisocial traits and / or Narcissistic traits (and / or Histrionic); they can also be extremely dissociative.
Some people want to re-label it to Complex Post Traumatic Stress Disorder.