Definitions

1. adjective

very close to a certain quality or standard, but not quite meeting it

“Her borderline personality disorder made it difficult for her to form close relationships.”

2. noun

a person or thing that is very close to a certain quality or standard, but not quite meeting it

“The movie’s borderline humor made it unsuitable for children.”

3. adverb

in a way that is very close to a certain quality or standard, but not quite meeting it

“She was borderline rude in her response to the customer’s complaint.”