diameter

noun

di·​am·​e·​ter dī-ˈa-mə-tər How to pronounce diameter (audio)
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
diametral 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.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The underground pipe is 30 inches in diameter and has been in operation since 1953. Laura Schulte, Journal Sentinel, 15 Nov. 2024 She was surrounded by three-foot diameter paper murals of Disney scenes attached to the wall with sticky putty that left dime-sized oil stains for months. Heather M. Jones, Parents, 6 Nov. 2024 And its models say that traffic diversion will increase levels of PM10, particulate matter with a diameter of 10 microns or less that harms the hugs and heart and is commonly emitted from vehicles and construction sites. Rachel Uranga, Los Angeles Times, 4 Nov. 2024 The fall is when trees put on the majority of their trunk diameter growth. Paul Cappiello, The Courier-Journal, 1 Nov. 2024 See all Example Sentences for diameter 

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

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

Dictionary Entries Near diameter

Cite this Entry

“Diameter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diameter. Accessed 6 Dec. 2024.

Kids Definition

diameter

noun
di·​am·​e·​ter dī-ˈam-ət-ər How to pronounce diameter (audio)
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 How to pronounce diameter (audio)
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
Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!