diameter

noun
di·​am·​e·​ter | \ dī-ˈa-mə-tər How to pronounce diameter (audio) \

Definition of diameter

1 mathematics : a chord (see chord entry 3 sense 2) passing through the center of a figure or body
2 mathematics : the length of a straight line through the center of an object or space the diameter of a circle dug a hole nearly four feet in diameter
3 physics : a unit of enlargement used with a number to indicate magnification by a lens or optical system an object one millimeter wide magnified 40 diameters appears 40 millimeters wide

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Other Words from diameter

diametral \ -​ˈa-​mə-​trəl How to pronounce diametral (audio) \ adjective

Examples of diameter in a Sentence

The dotted line indicates the diameter of the circle. What is the diameter of the tree trunk? Dig a hole that's two feet deep and three feet in diameter.
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Recent Examples on the Web

The Zhuque-1 booster is 19 meters tall, with a 1.3-meter diameter and a thrust of 45 tons. Eric Berger, Ars Technica, "Rocket Report: SpaceX targeted, Chinese rocket scientist goes viral, SLS slips?," 5 Oct. 2018 The engines are similarly huge, running 11 feet in diameter, with 16 fan blades crammed into a 14-foot engine capsule. Sam Blum, Popular Mechanics, "GE's Enormous New Jet Engines Sound Fiercely Loud in Runway Test," 17 Jan. 2019 Nicknamed Bertha after former Seattle Mayor Bertha Knight Landes, who served in the 1920s, the machine measured 57 feet, 4 inches in diameter and weighed more than 6,700 tons. Michelle Baruchman, The Seattle Times, "A look back at the Alaskan Way Viaduct as its demise — and the new Highway 99 tunnel — draw near," 7 Jan. 2019 The industry standard for such is that the unit must be able to remove at least 99.97% of particulates measuring 0.3 micron diameter in a lab setting. Rachel Rothman, Good Housekeeping, "Do Air Purifiers Actually Work?," 17 Dec. 2018 Those big ships had dominated the seas with their big guns, which measured up to 18 inches in diameter in the case of Japan’s Yamato class, with ranges of up to 20 nautical miles. Kyle Mizokami, Popular Mechanics, "As It Begins Its Second Century, Is the Aircraft Carrier Obsolete?," 5 Nov. 2018 But thanks to Juno, scientists have now discovered a huge cyclone at each pole, about 2,500 miles in diameter in the north and 3,500 miles in the south. Andrew Coates, Newsweek, "NASA Juno Unlocks Secrets of Jupiter's Mega Cyclone Clusters," 8 Mar. 2018 But this directional antenna aims signals in a spot beam, covering an area just 120 miles in diameter but blasting the signal at high power. Joe Pappalardo, Popular Mechanics, "USAF's Next-Gen GPS Satellites Will Be a Huge Upgrade...Eventually," 26 Dec. 2018 Due to the resolution of the satellite images, smaller burial mounds from about three to five meters (9.8 to 16.4 feet) in diameter didn’t show up or were too hard to distinguish from rock outcrops and other natural terrain. Kiona N. Smith, Ars Technica, "Satellites watch over the graves of ancient steppe nomads," 26 Dec. 2018

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

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First Known Use of diameter

14th century, in the meaning defined at sense 1

History and Etymology for diameter

Middle English diametre, from Middle French, from Latin diametros, from Greek, from dia- + metron measure — more at measure

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Statistics for diameter

Last Updated

18 Mar 2019

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Time Traveler for diameter

The first known use of diameter was in the 14th century

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More Definitions for diameter

diameter

noun

English Language Learners Definition of diameter

: a straight line from one side of something (such as a circle) to the other side that passes through the center point
: the distance through the center of something from one side to the other

diameter

noun
di·​am·​e·​ter | \ dī-ˈa-mə-tər How to pronounce diameter (audio) \

Kids Definition of diameter

1 : a straight line that runs from one side of a figure and passes through the center Measure the diameter of the circle.
2 : the distance through the center of an object from one side to the other : thickness the diameter of a tree trunk

diameter

noun
di·​am·​e·​ter | \ dī-ˈam-ət-ər How to pronounce diameter (audio) \

Medical Definition of diameter

1 : a unit of magnification for an optical instrument equal to the number of times the linear dimensions of an object are apparently increased a microscope magnifying 60 diameters
2 : one of the maximal breadths of a part of the body the transverse diameter of the inlet of the pelvis

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More from Merriam-Webster on diameter

Rhyming Dictionary: Words that rhyme with diameter

Spanish Central: Translation of diameter

Nglish: Translation of diameter for Spanish Speakers

Britannica English: Translation of diameter for Arabic Speakers

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