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
The specific type of drones the Chaska police are looking to acquire are the DJI Matrice series M30t, a modular drone about two feet in diameter able to carry various types equipment such as cameras.
—
Graham P. Johnson, Twin Cities, 7 Feb. 2025
As for the wheels, both are 12 inches in diameter, while the braking system includes a front disc brake and a rear drum brake.
—New Atlas, 7 Feb. 2025
The asteroid, being monitored by multiple space agencies across the world, is about 90 meters in diameter.
—Yaakov Katz, Newsweek, 7 Feb. 2025
The spots are tiny, less than 2 millimeters in diameter (similar to the tip of a pen).
—Brandi Jones, Msn-Ed, Health, 7 Feb. 2025
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Graham P. Johnson, Twin Cities, 7 Feb. 2025
As for the wheels, both are 12 inches in diameter, while the braking system includes a front disc brake and a rear drum brake.
—New Atlas, 7 Feb. 2025
The asteroid, being monitored by multiple space agencies across the world, is about 90 meters in diameter.
—Yaakov Katz, Newsweek, 7 Feb. 2025
The spots are tiny, less than 2 millimeters in diameter (similar to the tip of a pen).
—Brandi Jones, Msn-Ed, Health, 7 Feb. 2025
See all Example Sentences for diameter
Dictionary Entries Near diameter
Cite this Entry
“Diameter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diameter. Accessed 13 Feb. 2025.
Copy CitationKids 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
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