Meaning & use
perimeter
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Meanings
nouncountablemathematics
The total length of the boundary around a flat shape or area.
Grammar: Often used with 'of': the perimeter of a square. Can be used with 'calculate', 'find', 'measure'.
Patterns
- the perimeter of something
- calculate the perimeter
- find the perimeter
To find the perimeter of a rectangle, add the lengths of all four sides.
The perimeter of the garden is 20 meters, so we need 20 meters of fencing.
She measured the perimeter of the room before buying wallpaper.
nouncountable
The outer edge or boundary of an area, especially a guarded or enclosed one.
Grammar: Often used with 'around' or 'on': security around the perimeter, guards on the perimeter.
Patterns
- around the perimeter
- on the perimeter
- the perimeter fence
Security guards patrol the perimeter of the airport at night.
A high fence runs around the perimeter of the prison.
We walked around the perimeter of the old city walls.
Word forms
| plural | perimeters |
|---|
Common combinations
- perimeter fence
- The perimeter fence kept animals out of the garden.
- calculate the perimeter
- In math class, we learned to calculate the perimeter of polygons.
- security perimeter
- Police set up a security perimeter around the crime scene.
- around the perimeter
- Trees were planted around the perimeter of the field.
Synonyms and how they differ
- boundary
- A line that marks the limit of an area; 'perimeter' often refers to the measured length of that line, while 'boundary' can be more abstract.
- outline
- The outer shape or contour; 'perimeter' is more technical and often involves measurement.
- circumference
- Specifically the perimeter of a circle; 'perimeter' is used for any shape but not usually for circles in everyday speech.
Opposites
Word family
- perimetric adjective
- Relating to a perimeter; technical.
- perimetrically adverb
- In a way that relates to a perimeter; rare.
Commonly confused: perimeter or area? perimeter or parameter?
perimeter vs area
Area measures the space inside a shape (in square units), while perimeter measures the distance around it (in linear units). For a square with side 2, area is 4 square units and perimeter is 8 units.
perimeter vs parameter
A parameter is a limit or a numerical characteristic; 'perimeter' is the distance around a shape. They sound similar but have different meanings.
Practice
What is the perimeter of a square with sides of length 5 cm?
Choose one answer.
The perimeter is the total distance around the square, so you add all four sides: 5 + 5 + 5 + 5 = 20 cm. 10 cm would be only two sides, and 25 cm² would be the area.
Make it your own
Write a sentence using “perimeter”, then check it and compare it with the examples above.