perimeter

noun
pe·​rim·​e·​ter | \ pə-ˈri-mə-tər How to pronounce perimeter (audio) \

Definition of perimeter

1a : 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

Keep scrolling for more

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 On the perimeter, starters Both Gach and Gabe Kalscheur and reserve Jamal Mashburn Jr. combined for 33 points and seven of the team's nine three-pointers. Marcus Fuller, Star Tribune, "Can the Gophers and Marcus Carr end their road struggles Wednesday night at Michigan?," 6 Jan. 2021 With eight defenders in the box, there’s single coverage out on the perimeter. cleveland, "Previewing the Ohio State-Alabama CFP Championship: Jimmies and Joes vs. X’s and O’s," 6 Jan. 2021 The Cornhuskers’ length is difficult to simulate in practice, which gives the Spartans some problems early on the perimeter. Chris Solari, Detroit Free Press, "No. 18 Michigan State basketball at Nebraska: Scouting report, prediction," 1 Jan. 2021 Moody also assisted on a layup for KK Robinson, who made a nice backdoor cut to counter ACU's pressure on the perimeter. Arkansas Online, "Hogs beat Abilene Christian without Musselman," 23 Dec. 2020 Tulane’s Gabe Watson had his back to the basket with a Grambling defender guarding him tightly on the perimeter Saturday. G Smith, NOLA.com, "No space required: Tulane guard Gabe Watson a master of tough shots," 21 Dec. 2020 With two threats on the perimeter, along with dynamic tight end Jonnu Smith, the Titans have enough weapons in the passing attack that the need to utilize Henry – who's not much of a receiver – in that way isn’t necessary. Chris Bumbaca, USA TODAY, "Seven reasons why Tennessee Titans' Derrick Henry can become eighth NFL player with 2,000 rushing yards," 17 Dec. 2020 His speed and burst to outrun pursuit angles on the perimeter are impressive. John Owning, Dallas News, "Film room: 3 things we learned from Cowboys-Bengals, including why RB-by-committee is the way for Dallas to go," 14 Dec. 2020 Trent’s aggressiveness on the perimeter, getting in the faces of scorers and relentlessly harassing them, has impressed Simons. oregonlive, "Still developing Anfernee Simons searches for role within Portland Trail Blazers’ crowded backcourt," 4 Dec. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'perimeter.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of perimeter

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

History and Etymology for perimeter

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

Keep scrolling for more

Learn More about perimeter

Time Traveler for perimeter

Time Traveler

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

See more words from the same century

Statistics for perimeter

Last Updated

20 Jan 2021

Cite this Entry

“Perimeter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/perimeter. Accessed 20 Jan. 2021.

Keep scrolling for more

More Definitions for perimeter

perimeter

noun
How to pronounce perimeter (audio)

English Language Learners Definition of perimeter

: the outside edge of an area or surface
: the total length of the lines that form a shape
basketball : the area on a basketball court that is not close to the basket

perimeter

noun
pe·​rim·​e·​ter | \ pə-ˈri-mə-tər How to pronounce perimeter (audio) \

Kids Definition of perimeter

1 : the whole outer boundary of a figure or area
2 : the length of the boundary of a figure

perimeter

noun
pe·​rim·​e·​ter | \ pə-ˈrim-ət-ər How to pronounce perimeter (audio) \

Medical Definition of perimeter

1a : 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

Keep scrolling for more

Comments on perimeter

What made you want to look up perimeter? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

Test Your Vocabulary

Words of Snow and Ice Quiz

  • image1037863653
  • Which of the following refers to thin, bending ice, or to the act of running over such ice?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Typeshift

Anagram puzzles meet word search.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!