• synonyms


See more synonyms for perimeter on Thesaurus.com
  1. the border or outer boundary of a two-dimensional figure.
  2. the length of such a boundary.
  3. a line bounding or marking off an area.
  4. the outermost limits.
  5. Military. a fortified boundary that protects a troop position.
  6. Ophthalmology. an instrument for determining the peripheral field of vision.
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Origin of perimeter

1585–95; < French périmètre < Latin perimetros (feminine) < Greek perímetron (neuter). See peri-, -meter
Related formspe·rim·e·ter·less, adjectivepe·rim·e·tral, per·i·met·ric [per-uh-me-trik] /ˌpɛr əˈmɛ trɪk/, per·i·met·ri·cal, adjectiveper·i·met·ri·cal·ly, adverbpe·rim·e·try, noun
Can be confusedparameter perimeter
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words

boundary, edge, periphery, confines, fringe, ambit, brim, borderline, skirt, circuit, limit, verge, compass, hem, margin, brink, outline

Examples from the Web for perimeter

Contemporary Examples

Historical Examples

  • There were guards surrounding the perimeter with radar search beams.

    A Spaceship Named McGuire

    Gordon Randall Garrett

  • The Radius is a right line drawne from the center to the perimeter.

  • Also, the lowest part of the perimeter of a geometrical figure.

    The Sailor's Word-Book

    William Henry Smyth

  • But that multiplication, is a multiplication of the Perpendicular by the Perimeter or bout-line.

  • The perimeter of a figure is the outer boundary or measure around it.


    Elmer W. Cavins

British Dictionary definitions for perimeter


  1. maths
    1. the curve or line enclosing a plane area
    2. the length of this curve or line
    1. any boundary around something, such as a field
    2. (as modifier)a perimeter fence; a perimeter patrol
  2. a medical instrument for measuring the limits of the field of vision
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Derived Formsperimetric (ˌpɛrɪˈmɛtrɪk) or perimetrical, adjectiveperimetrically, adverbperimetry, noun

Word Origin

C16: from French périmètre, from Latin perimetros; see peri-, -meter
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for perimeter


early 15c., "line around a figure or surface," from Latin perimetros, from Greek perimetron "circumference," from peri- "around" (see peri-) + metron "measure" (see meter (n.2)). Military sense of "boundary of a defended position" is attested from 1943.

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Online Etymology Dictionary, © 2010 Douglas Harper

perimeter in Medicine


  1. The outer limits of an area; circumference.
  2. An instrument used to measure field of vision.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

perimeter in Science


  1. The sum of the lengths of the segments that form the sides of a polygon.
  2. The total length of any closed curve, such as the circumference of a circle.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.