I. bor ‧ der ‧ line 1 /ˈbɔːdəlaɪn $ ˈbɔːrdər-/ BrE AmE adjective
1 . very close to not being acceptable:
In borderline cases, the student’s coursework is considered, as well as exam grades.
The referee’s decision was borderline.
2 . [usually before noun] having qualities of both one situation, state etc and another more extreme situation or state:
a borderline schizophrenic (=someone who has some signs of being mentally ill)
II. borderline 2 BrE AmE noun
1 . [singular] the point at which one quality, situation, emotion etc ends and another begins:
She slipped over the borderline into sleep.
on the borderline
I was on the borderline between a first- and a second-class degree.
2 . [countable] a border between two countries