1. the outer boundary or edge of a closed figure or area
Usage: mathematics; geometry
2. the length of the boundary line around a closed figure
Usage: mathematics
3. the outer limits or boundary of an area, especially one that is guarded or defended
Usage: military; security

Examples

• The perimeter of the rectangle is 20 inches.
• Security guards patrol the perimeter of the building.
• We walked around the perimeter of the park.
• Calculate the perimeter by adding all four sides.
• The fence marks the perimeter of our property.
• Soldiers established a defensive perimeter around the camp.
• The perimeter of a circle is called its circumference.