1. boundaries or dividing lines between two areas, countries, or regions
Usage: plural of borderline
2. points or conditions that are very close to a particular limit or category
Usage: often used in contexts involving qualification or classification

Examples

• The map clearly shows the borderlines between the three countries.
• Security is tight along the borderlines in this region.
• Her test scores put her right on the borderlines for admission.
• The doctor said his symptoms were on the borderlines of several conditions.
• These borderlines between acceptable and unacceptable behavior are often unclear.
• The artist's work explores the borderlines between reality and fantasy.