borderline

/ˈbɔːrdərlaɪn/
adjective
  1. On the edge of a particular condition or quality; not clearly one thing or another.
    • He made a borderline joke that made some people uncomfortable.
    • The patient's symptoms were borderline, making diagnosis difficult.
    • Her test score was borderline, so she had to retake the exam.
Antonyms
noun
  1. A dividing line or boundary between two states or conditions.
    • The river formed the borderline between the two farms.
    • The borderline between genius and madness can be thin.
    • They lived right on the borderline between two time zones.
What does "borderline" mean? | whatsthatwordmean | whatsthatwordmean