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diameter

American  
[dahy-am-i-ter] / daɪˈæm ɪ tər /

noun

  1. Geometry.

    1. a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.

    2. a straight line passing from side to side of any figure or body, through its center.

  2. the length of such a line.

  3. the width of a circular or cylindrical object.


diameter British  
/ daɪˈæmɪtə /

noun

    1. a straight line connecting the centre of a geometric figure, esp a circle or sphere, with two points on the perimeter or surface

    2. the length of such a line

  1. the thickness of something, esp with circular cross section

"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

diameter Scientific  
/ dī-ămĭ-tər /
  1. A straight line segment that passes through the center of a circle or sphere from one side to the other.

  2. The length of such a line segment.


diameter Cultural  
  1. A straight line passing through the center of a figure, especially a circle or sphere, and joining two opposite points on its circumference.


Etymology

Origin of diameter

First recorded in 1350–1400; Middle English diametre, from Old French, from Latin diametros, from Greek diámetros “diagonal, diameter,” from dia- dia- + -metros, derivative of métron meter 1

Explanation

It's good to know where the diameter of a circular object is if you have to split a cookie between two 5-year-old kids. Think of a round chocolate chip cookie. The diameter of the cookie is a line that divides the cookie into two equal halves, through the center of the cookie. The diameter of a circle or sphere is a line that passes through the center and starts and ends and two opposite points on its perimeter or edge. The diameter is also the length of that line. In math class, teachers often ask you to use the diameter of a circle to find its area. This is a good skill to have if you are trying to figure out whether the 14 inch or 16 inch pizza is a better deal.

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Vocabulary lists containing diameter

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Soccer sought outside help, funding what is reported to be a two-year, $12-million deal with donations from hedge fund billionaire Kenneth C. Griffin, Diameter Capital co-founder Scott Goodwin and others.

From Los Angeles Times • Oct. 11, 2024

In April, Diameter Capital closed a $2.2 billion special situations debt fund, which data provider Prequin at the time said was the largest of its kind so far this year.

From Reuters • May 8, 2023

The United States has offered to send munitions known as Ground Launched Small Diameter Bombs, which have a range of 90 miles.

From New York Times • Apr. 21, 2023

The F-22 weapons complement includes ground-specific attack weapons such as Joint Direct Attack Munitions – such as the GBU 32 and GBU 39 -- and the Small Diameter Bomb.

From Fox News • Jun. 1, 2020

Diameter of cylinders 14 inches.Length of stroke 22 inches.

From Illustrated Catalogue of Locomotives Baldwin Locomotive Works by Baird, Matthew

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