borderline

[Victor Steinbok]

Borderline adj., borderline case (listed under borderline 2.) and
borderliner, as applied to "insanity", are in the OED. Borderline
personality, borderline personality disorder and subsequent
"borderline", meaning someone with borderline personality disorder, are
not. Note that the original borderline and derived borderline are not
equivalent, although they are clearly related.

> 2. attrib. or as adj. Occupying a border-line; esp. in phr.
> border-line case; spec.  (a) verging on the indecent or obscene;  (b)
> verging on insanity.

AHD4 does a somewhat better job:

> 1. a. Verging on a given quality or condition: borderline poverty.
>     b. Of a questionable nature or quality: an applicant with
> borderline qualifications.
> 2. a. Psychology: Relating to any phenomenon that is intermediate
> between two groups and not clearly categorized in either group: a
> borderline state showing the characteristics of both neurotic and
> psychotic reactions.
>     b.Relating to a condition characterized by a pattern of
> instability in mood, interpersonal relations, and self-image, and
> manifested by self-destructive, impulsive, and inconsistent behavior:
> the borderline syndrome.

     VS-)

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