diameter
noun
di·am·e·ter
dī-ˈa-mə-tər 
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
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.
Recent Examples on the Web
There were more than 90 storm reports Tuesday, including reports of hail as large as 4.25 inches in diameter across Texas.
—
Phil Helsel, NBC News, 10 Apr. 2024
Using a small nail (approximately 3mm in diameter) push a hole in the foil.
—John Bacon, USA TODAY, 8 Apr. 2024
The wire battery, which measures 1.4 millimeters in diameter and more than 20 centimeters long, uses a twisted copper fabric as a current collector.
—IEEE Spectrum, 5 Apr. 2024
The diner chain got that crazy large number by using the measurements of standard Denny’s pancake – six inches in diameter and three inches in radius, for a surface area of 28.27 square inches.
—The Indianapolis Star, 5 Apr. 2024
The magnitude is the fraction of the sun's diameter covered by the moon during the partial eclipse.
—Leah Sarnoff, ABC News, 4 Apr. 2024
Another vehicle’s passenger-side roof was pierced by a hole about two feet in diameter, but the windshield and side windows were virtually intact.
—Aric Toler, New York Times, 3 Apr. 2024
Mulanje cedar, a tropical conifer that grew to around 150 feet and could be five feet in diameter, is endemic to the Mulanje Mountains.
—Mark Jenkins, Smithsonian Magazine, 2 Apr. 2024
The transition has increased the size of the tunnels from 20 feet each in the twin-bore design to 53 feet in diameter for the most-recent single-bore option.
—Daniel Borenstein, The Mercury News, 29 Mar. 2024
Phil Helsel, NBC News, 10 Apr. 2024
Using a small nail (approximately 3mm in diameter) push a hole in the foil.
—John Bacon, USA TODAY, 8 Apr. 2024
The wire battery, which measures 1.4 millimeters in diameter and more than 20 centimeters long, uses a twisted copper fabric as a current collector.
—IEEE Spectrum, 5 Apr. 2024
The diner chain got that crazy large number by using the measurements of standard Denny’s pancake – six inches in diameter and three inches in radius, for a surface area of 28.27 square inches.
—The Indianapolis Star, 5 Apr. 2024
The magnitude is the fraction of the sun's diameter covered by the moon during the partial eclipse.
—Leah Sarnoff, ABC News, 4 Apr. 2024
Another vehicle’s passenger-side roof was pierced by a hole about two feet in diameter, but the windshield and side windows were virtually intact.
—Aric Toler, New York Times, 3 Apr. 2024
Mulanje cedar, a tropical conifer that grew to around 150 feet and could be five feet in diameter, is endemic to the Mulanje Mountains.
—Mark Jenkins, Smithsonian Magazine, 2 Apr. 2024
The transition has increased the size of the tunnels from 20 feet each in the twin-bore design to 53 feet in diameter for the most-recent single-bore option.
—Daniel Borenstein, The Mercury News, 29 Mar. 2024
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'diameter.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
Dictionary Entries Near diameter
Cite this Entry
“Diameter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diameter. Accessed 19 Apr. 2024.
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Kids Definition
diameter
noun
di·am·e·ter
dī-ˈam-ət-ər
1
: a straight line passing through the center of a figure or body
especially
: a line segment through the center of a circle with its ends on the circle's circumference
2
: the length of a diameter
Medical Definition
diameter
noun
di·am·e·ter
dī-ˈam-ət-ər
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
More from Merriam-Webster on diameter
Thesaurus: All synonyms and antonyms for diameter
Nglish: Translation of diameter for Spanish Speakers
Britannica English: Translation of diameter for Arabic Speakers
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