- on or near a border or boundary.
- uncertain; indeterminate; debatable: not an alcoholic, but a borderline case.
- not quite meeting accepted, expected, or average standards.
- approaching bad taste or obscenity: He made several borderline remarks that offended them.
- a person suffering from borderline personality.
- a border; dividing line; line of demarcation
- an indeterminate position between two conditions or qualitiesthe borderline between friendship and love
- on the edge of one category and verging on anothera borderline failure in the exam