1. （两种不同或相反事物之间的）分界线
    The borderline between two different or opposite things is the division between them.

    e.g. ...a task which involves exploring the borderline between painting and photography.
           一项探究绘画与摄影之间界线的工作

2. 勉强可以的；刚刚够格的
    Something that is borderline is only just acceptable as a member of a class or group.

borderline的反义词

    e.g. Some were obviously unsuitable and could be ruled out at once. Others were borderline cases.
           一些明显不合适，可以马上排除。另一些则勉强合格。

1. a line that indicates a boundary

    Synonym: boundary lineborderdelimitationmete

1. of questionable or minimal quality

    e.g. borderline grades
           marginal writing ability

    Synonym: marginal