Definition of borderlines:
(adj) :
Nearly; not clearly on one side or the other of a border or boundary, ambiguous.
(adj) :
Of questionable taste or acceptability; approaching bad taste.
(adj) :
Exhibiting borderline personality disorder.
(adv) :
Nearly; not entirely but nevertheless to a great extent.
(n) :
(countable) A boundary or accepted division; a border.
(n) :
(countable) A person who has borderline personality disorder.