Borderline (adjective)

1. Relating to or being on or near a border.
2. Just within the limits of what is acceptable or permissible.
3. Having some of the characteristics of a particular thing or condition, but not enough to be a typical example of it.

Origin:

Late 19th century: from border + -line.

Examples:

1. The new housing development is located on the borderline between the city and the countryside.
2. The behavior of the employee was considered borderline unacceptable, and he was given a warning.
3. She had borderline diabetes, her blood sugar was only slightly elevated.
4. The movie received mixed reviews, some called it a masterpiece, others found it borderline boring.
5. The company's profits were on the borderline of what was considered acceptable for the industry.