Other forms: perimeters
The perimeter is the distance all the way round the outside of a shape. Calculate the perimeter, the perimeter of a rectangle, walk the perimeter.
In geometry it is a length, and it is measured in the same units as the sides; the area inside is measured in square units, which is the distinction most often muddled. Circumference is the special name for a circle's perimeter. In security and military use, the perimeter is the outer boundary of a site: a perimeter fence, secure the perimeter, a perimeter breach. Note perimeter road, which runs round the edge of an airfield.
1nounperimeterThe distance all the way round the outside of a shape.
“The perimeter is twice the length plus twice the width.”
2nounboundaryThe outer boundary of a site.
“A tall fence runs around the perimeter of the airport.”
Too few real examples of this word to estimate which sense is commonest.
perimeter is a boundary or its length.
Greek perimetros is peri-, around, plus metron, a measure. The same peri- gives period and periscope, and the same metron gives metre, thermometer and geometry — measuring the earth.
Ancient Greek
περίμετρος
Latin
perimetros
English, today
perimeter
From Latin perimetros, Ancient Greek περίμετρος. Equivalent to peri- + meter.
Etymology from Wiktionary, CC BY-SA