nearly; not clearly on one side or the other of a border or boundary, ambiguous. / Showing bad taste. / Exhibiting borderline personality disorder.

Nearly; not entirely but nevertheless to a great extent.

(countable) A boundary or accepted division; a border. / (uncountable) Short for borderline personality disorder. / (countable) An individual who has borderline personality disorder.

(transitive) To border, or border on; to be physically close or conceptually akin to.

plural of borderline

The quality of being borderline.

plural of borderliner

(informal) An individual who has borderline personality disorder.

simple past tense and past participle of borderline

present participle of borderline