Definition of perimeter in US English:



  • 1The continuous line forming the boundary of a closed geometric figure.

    ‘the perimeter of a rectangle’
    • ‘The perimeter of the inner polygon is shorter than the circumference of the circle, while that of the outer polygon is longer.’
    • ‘It is easier to find a pentagon that circumscribes the same circle as the given square and has the same perimeter.’
    • ‘Finally, if the rope is short enough (less than half the perimeter of the barn), the problem simplifies immensely.’
    • ‘The most interesting results show, with a very ingenious proof, that an equilateral triangle has a greater area than any isosceles or scalene triangle with the same perimeter.’
    • ‘The square and the cube are abstract, they're mathematical forms, measurements, perimeters, boundaries, mental constructs, and as such, are emotionally unknowable.’
    • ‘Zenodorus studied the area of a figure with a fixed perimeter and the volume of a solid figure with fixed surface.’
    • ‘He compares the areas of figures with equal perimeters and volumes of solids with equal surface areas, proving a result due to Zenodorus that the sphere has greater volume than any regular solid with equal surface area.’
    • ‘Answer: the arc lengths and, therefore, the perimeters are equal.’
    • ‘We found that the area, perimeter, length, and width of the lamina were highly correlated, suggesting the existence of a common genetic control.’
    • ‘The number four, for example, would be the ratio of the perimeter of a square to one of its sides and also the ratio of the area of a square to the area of a square whose side is half the original.’
    • ‘You calculate the perimeter by multiplying the diameter by pi.’
    • ‘Then these rings also have the additional property that both the inner perimeters are equal and the outer perimeters are equal.’
    circumference, outside, outer edge
    View synonyms
    1. 1.1 The outermost parts or boundary of an area or object.
      ‘the perimeter of the garden’
      figurative ‘my presence on the perimeter of his life’
      • ‘Signs are being placed around airport perimeters urging them to join the cause.’
      • ‘About 30 minutes after they had started out, they arrived just beyond the outer perimeter of the lab area.’
      • ‘For the less energetic, there is a walk around the perimeter racecourse road beginning at 2 pm.’
      • ‘I drove around our perimeter road one rainy night and saw lots of little rodents of some type running around.’
      • ‘Repeat this until the entire perimeter of the room has been sanded.’
      • ‘The court heard how she made off with thousands of pounds worth of holidaymakers' property after scaling the perimeter fence and entering the rooms.’
      • ‘There were wooded areas beyond the perimeter and alongside one of the streams, but the course itself was mostly just a large empty field.’
      • ‘They ran to a perimeter concrete fence and jumped over.’
      • ‘He said it was the landlord of the estate who had replaced the perimeter fence around the whole of the industrial area.’
      • ‘One is a low-voltage electric fence around the perimeter of your garden.’
      • ‘Most styles can be adapted to meet any pool codes in your area, and provide a safe perimeter fence around your pool.’
      • ‘There are lots of grasshoppers around here, but my hens patrol the garden perimeter fence and really reduce the numbers of insects in the garden.’
      • ‘A two-kilometre perimeter fence for the broader area is also planned.’
      • ‘We could walk the entire perimeter of the island in less than an hour.’
      • ‘Sub-zero temperatures at the complex left the narrow perimeter roads covered in sheet ice, with virtually no grip for the opening cars.’
      • ‘The only sure way of deterring them is to have an electric fence built around the perimeter of the garden.’
      • ‘Surrounding the entire perimeter of the fence was a long line of barbed wire, spiky and foreboding.’
      • ‘Burn some sage, and walk the inner perimeter of your room or home if you can.’
      • ‘A tough protein envelope surrounds the inner perimeter of the cell.’
      • ‘After dark I drove the perimeter road and saw more jackals and foxes.’
      boundary, border, frontier, limits, outer limits, bounds, confines, edge, margin, fringe, fringes, periphery, borderline, verge
      View synonyms
    2. 1.2 A defended boundary of a military position or base.
      • ‘In their current formation, they were able to observe every inch of the camp perimeter.’
      • ‘Bitter fighting ensued and the enemy overran forward elements, infiltrated the perimeter and rendered friendly positions untenable.’
      • ‘Our battalion promptly relieved the Marine battalion in place, freeing it to plan for its attack within the safety of the Army's perimeter.’
      • ‘The troops were tasked with planning the defense of the squadron and performing defensive operations around the base perimeter.’
      • ‘If the enemy builds an outer defensive perimeter around the city, it has to be taken in two stages.’
      • ‘One of the challenges of such a collective training event is finding a location to set up a support base camp that allows live fire from within the perimeter.’
      • ‘They were stationed around the perimeter of the base.’
      • ‘The Kiwis do security patrols around the base perimeter and man the watchtower on a roster system.’
      • ‘Once, the primary goal was to protect network perimeters.’
      • ‘Ahead of us is a large cave entrance protected by a perimeter of military guards and equipment.’
      • ‘Military personnel will also have access from inside the camp perimeter.’
      • ‘He immediately set up a defensive perimeter and fortified his area.’
      • ‘Beyond the defensive perimeters of many castles the vestiges of medieval market places can still be found, often with market crosses.’
      • ‘Simultaneously, they would seize territory throughout the Pacific Rim and attempt to establish a strategic defensive perimeter.’
      • ‘She didn't patrol the base perimeter to repel insurgents.’
      • ‘However, e-mail content filters that look for viral patterns using anti-virus engines will help defend your network perimeter.’
      • ‘Andrews and the crew quickly exited the aircraft and established a defensive perimeter.’
      • ‘Our job was to scout, observe and report on enemy activity in the vast area beyond our perimeter.’
      • ‘Stationary truckloads of sand parked at the mouth of every street bear an eerie resemblance to a military perimeter.’
      • ‘The idea of trained guards patrolling a secure perimeter is a good one.’
    3. 1.3Basketball An area away from the basket, beyond the reach of the defensive team.
      ‘he was very patient in working the ball around the perimeter’
      • ‘He's also beginning to get a feel for the right time to squeeze off a tough shot and when to flick the ball out to the perimeter and restart.’
      • ‘With reduced defensive contact on the perimeter, point guards can do their jobs with less harassment.’
      • ‘More than anything, the team needs his defense on the perimeter against more athletic swingmen.’
      • ‘The low post has two options as the ball moves around the perimeter.’
      • ‘That is to say, whenever the ball is on the perimeter, 3 defensive players are between the player with the ball and basket.’
  • 2An instrument for measuring the extent and characteristics of a person's field of vision.


See parameter


Late Middle English: via Latin from Greek perimetros, based on peri- ‘around’ + metron ‘measure’.