Definition of perimeter in English:



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

    ‘the perimeter of a rectangle’
    • ‘Answer: the arc lengths and, therefore, the perimeters are equal.’
    • ‘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.’
    • ‘Finally, if the rope is short enough (less than half the perimeter of the barn), the problem simplifies immensely.’
    • ‘Then these rings also have the additional property that both the inner perimeters are equal and the outer 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.’
    • ‘The square and the cube are abstract, they're mathematical forms, measurements, perimeters, boundaries, mental constructs, and as such, are emotionally unknowable.’
    • ‘You calculate the perimeter by multiplying the diameter by pi.’
    • ‘It is easier to find a pentagon that circumscribes the same circle as the given square and has the same perimeter.’
    • ‘Zenodorus studied the area of a figure with a fixed perimeter and the volume of a solid figure with fixed surface.’
    • ‘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 perimeter of the inner polygon is shorter than the circumference of the circle, while that of the outer polygon is longer.’
    circumference, outside, outer edge
    View synonyms
    1. 1.1The outermost parts or boundary of an area or object.
      ‘the perimeter of the garden’
      [as modifier] ‘a perimeter fence’
      • ‘A tough protein envelope surrounds the inner perimeter of the cell.’
      • ‘He said it was the landlord of the estate who had replaced the perimeter fence around the whole of the industrial area.’
      • ‘Most styles can be adapted to meet any pool codes in your area, and provide a safe perimeter fence around your pool.’
      • ‘About 30 minutes after they had started out, they arrived just beyond the outer perimeter of the lab area.’
      • ‘We could walk the entire perimeter of the island in less than an hour.’
      • ‘Repeat this until the entire perimeter of the room has been sanded.’
      • ‘Surrounding the entire perimeter of the fence was a long line of barbed wire, spiky and foreboding.’
      • ‘There were wooded areas beyond the perimeter and alongside one of the streams, but the course itself was mostly just a large empty field.’
      • ‘Sub-zero temperatures at the complex left the narrow perimeter roads covered in sheet ice, with virtually no grip for the opening cars.’
      • ‘I drove around our perimeter road one rainy night and saw lots of little rodents of some type running around.’
      • ‘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.’
      • ‘For the less energetic, there is a walk around the perimeter racecourse road beginning at 2 pm.’
      • ‘Burn some sage, and walk the inner perimeter of your room or home if you can.’
      • ‘One is a low-voltage electric fence around the perimeter of your garden.’
      • ‘They ran to a perimeter concrete fence and jumped over.’
      • ‘After dark I drove the perimeter road and saw more jackals and foxes.’
      • ‘The only sure way of deterring them is to have an electric fence built around the perimeter of the garden.’
      • ‘Signs are being placed around airport perimeters urging them to join the cause.’
      • ‘The court heard how she made off with thousands of pounds worth of holidaymakers' property after scaling the perimeter fence and entering the rooms.’
      boundary, border, frontier, limits, outer limits, bounds, confines, edge, margin, periphery, borderline, verge
      View synonyms
    2. 1.2Basketball An area away from the basket, beyond the reach of the defensive team.
      ‘he was very patient in working the ball 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.’
      • ‘The low post has two options as the ball moves around the perimeter.’
      • ‘More than anything, the team needs his defense on the perimeter against more athletic swingmen.’
      • ‘With reduced defensive contact on the perimeter, point guards can do their jobs with less harassment.’
      • ‘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.’
  • 2An instrument for measuring the extent and characteristics of a person's field of vision.


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