perimeter

B2 · Upper Intermediate Countable noun

n. the outer edge or border of a specific area, like a building or a park.

n. the outermost limits or boundary of a physical area or complex.

“Security guards patrol the perimeter of the airport every hour.”

“The protesters gathered just outside the perimeter of the embassy, held back by a line of temporary steel fencing.”

C1 · Advanced Countable noun Technical

n. a protected line around a military position.

n. a fortified boundary or defensive line established to protect a military installation or position.

“The soldiers worked quickly to secure the perimeter before nightfall.”

“The commander ordered the troops to reinforce the western perimeter, fearing that the dense forest provided too much cover for an enemy advance.”

C2 · Proficiency Countable noun Medicine Technical

n. a tool used by doctors to measure how far you can see to the sides.

n. an instrument used in ophthalmology to map the extent and sensitivity of a patient's visual field.

“The eye doctor used a perimeter to check if the patient had lost any side vision.”

“Automated perimeters have largely replaced manual testing for detecting early signs of glaucoma in clinical practice.”