"borderline" definition, meaning, and origin

Adjective

Nearly; not clearly on one side or the other of a border or boundary, ambiguous.
- I would rather hire a talented layman than a university graduate with borderline qualifications.
- It recalls the business case for Scotland's reopening of the Borders Railway to Tweedbank, that British Rail closed in 1969. The review says the business case for this was at best borderline, but goes on to say that the...
Of questionable taste or acceptability; approaching bad taste.
- Your borderline remarks about my aunt’s dress destroyed my evening.
Exhibiting borderline personality disorder.
- She clearly has borderline and narcissistic features and she meets the criteria for a rapid cycling bipolar disorder, as well as for a generalized anxiety disorder. She has a severe binge eating disorder and has gained...

From border + line.

Nearly; not entirely but nevertheless to a great extent.
- He is borderline hypoglycemic and needs to monitor his sugar intake.
- I expected him to be super boring but he was actually borderline funny!

A boundary or accepted division; a border.
- She lives on the borderline between reality and madness.
- Elbow deep inside the borderline Show me that you love me and that we belong together Shoulder deep within the borderline Relax, turn around and take my hand - 1996, “Stinkfist”, performed by Tool:
Ellipsis of borderline personality disorder.
- The four overlapping concepts of borderline were as follows : (1) A residual model […] (2) An affective disorder model, which considered BPD as an affective spectrum illness displaying prominent[…] - 2001 July 23,...
- [...] you should consider it! People with Borderline are especially affected by the unconditional affection parenting a pet can provide. - 2014 December 16, Amber Zufelt, Chasing Butterflies: The Ultimate Guide to...
- Subsequent conceptualizations of borderline were based on important contributions from psychoanalysts, […] As a result of its inclusion, appearing as “borderline personality disorder,” the construct gained legitimacy[…]...
A person who has borderline personality disorder.
- As an example of their affective profile, borderlines are set apart from passive aggressives by having more marked social anxiety […] and greater sensitivity […] - 1995, Eugene E. Levitt, Edward Earl Gotts, The Clinical...