perimeter

noun

pe·​rim·​e·​ter pə-ˈri-mə-tər How to pronounce perimeter (audio)
1
a
: the boundary of a closed plane figure
b
: the length of a perimeter
2
: a line or strip bounding or protecting an area
3
: outer limits
often used in plural
4
: the part of a basketball court outside the three-point line

Did you know?

Parameter vs. Perimeter

It's very easy to confuse parameter with perimeter. Not only do the two words sound the same, they both connote a boundary or limit.

When parameter is used to mean "a boundary or limit," it is usually in its plural form, and often as the object of a preposition such as within or beyond:

Let's face it, managing weight loss or maintenance can be trying enough within the parameters of a daily routine.
Geoff Kerr, Weight Watchers, November 1991

Though candor sometimes encourages Bruno to "stray beyond the parameters of good taste," his interaction with Lydia is always convincingly portrayed as a loving, tender relationship.
Ron Charles, The Washington Post, 8 Feb. 2011

In geometry, perimeter refers to the boundary of a closed plane figure. You might remember calculating perimeters in school. If each side of an equilateral triangle measures 9 feet, then the perimeter of the triangle measures 27 feet. In more general use, perimeter describes an outer stretch, as in "The college president lived in a house on the perimeter of the campus."

Parameter originally had a meaning pertaining to mathematics as well. The dictionary defines it as "an arbitrary constant whose value characterizes a member of a system (as a family of curves); also : a quantity (as a mean or variance) that describes a statistical population" as well as "an independent variable used to express the coordinates of a variable point and functions of them."

Some twentieth-century usage commentators objected to the use of a scientific-sounding word like parameter in general contexts (as in the examples above), especially to mean "a limit or boundary," theorizing that perimeter must have been what the speaker or writer intended.

However, perimeter was not often used in the phrasings that parameter is used in (that is, as the object of within or beyond) until much later. In fact, a word such as bounds or range or confines often serves as a more appropriate equivalent for parameter than the marginal connotations of perimeter:

But a true novel is an extended piece of fiction: Length is clearly one of its parameters.
Anthony Burgess, The New York Times Book Review, 5 Feb. 1984

Shields will then subsume that request in the overall City operating budget that he will recommend to the City Council in mid-March, and the Council will make its final decisions on the parameters of the budget, including any tax increases or cuts, by the end of April.
Nicholas F. Benton, The Falls Church News Press, 6 Jan. 2016

Did you know?

The perimeter of a prison is ringed with high walls and watchtowers, and the entire perimeter of Australia is bounded by water. In geometry, you may be asked to calculate the perimeter of various geometrical shapes. In basketball, the perimeter is the area beyond the free-throw circle; a "perimeter player" tends to stay outside that circle. Try not to confuse this word with parameter, which usually means a rule or limit that controls what something is or how it can be done.

Examples of perimeter in a Sentence

He scored from the perimeter. soldiers guarding the perimeter of the camp
Recent Examples on the Web Instead, the Mountain West’s worst perimeter shooting team played right into the hands of Boise State and cast up one 3 after another – and finished 6 of 25 behind the arc. Mark Zeigler, San Diego Union-Tribune, 9 Mar. 2024 After police established a perimeter around the house, a neighbor walked into the area and didn't leave after officers asked him to, Deanda said. Andrew Ford, The Arizona Republic, 5 Mar. 2024 Their perimeter defense was passive and their ball movement was bottled up by the active Trojans. Ben Bolch, Los Angeles Times, 25 Feb. 2024 The security perimeter takes up a large part of downtown. Journal Sentinel, 22 Feb. 2024 Cybersecurity Enhancement: With identities forming the new perimeter in cybersecurity, a CIDO can spearhead strategies to fortify this boundary against increasing cyber threats. Gregory Webb, Forbes, 22 Feb. 2024 In 1993, following the Oslo accords, Israel handed over some daily management of Gaza to the PA but retained effective domination with a permanent military presence, control over its land perimeter and airspace, and oversight of its finances and tax revenues. Marc Lynch, Foreign Affairs, 20 Feb. 2024 Three-pointers made per game: 5.3 (14th/last) Opponent 3-point percentage: 34.8% (9th) Kansas coach Bill Self pointed out KU’s perimeter shooting issues in December. Shreyas Laddha, Kansas City Star, 16 Feb. 2024 Video filmed on Tuesday at the hospital shows columns of smoke at its perimeter, an Israeli bulldozer destroying a hospital perimeter wall, and an armored vehicle entering the hospital grounds. Sana Noor Haq, CNN, 15 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'perimeter.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Middle English perimetre, from Latin perimetros, from Greek, from peri- + metron measure — more at measure

First Known Use

15th century, in the meaning defined at sense 1a

Time Traveler
The first known use of perimeter was in the 15th century

Dictionary Entries Near perimeter

Cite this Entry

“Perimeter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/perimeter. Accessed 19 Mar. 2024.

Kids Definition

perimeter

noun
pe·​rim·​e·​ter pə-ˈrim-ət-ər How to pronounce perimeter (audio)
: the boundary of a shape or area
also : the length of such a boundary

Medical Definition

perimeter

noun
pe·​rim·​e·​ter pə-ˈrim-ət-ər How to pronounce perimeter (audio)
1
a
: the boundary of a closed plane figure
b
: the length of a perimeter
2
: an instrument for examining the discriminative powers of different parts of the retina often consisting of an adjustable semicircular arm with a fixation point for the eye and variable stations for the visual stimuli

More from Merriam-Webster on perimeter

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