- a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.
- a straight line passing from side to side of any figure or body, through its center.
- the length of such a line.
- the width of a circular or cylindrical object.
Origin of diameter
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for diameter
Kepler-186f is about 11 percent larger than Earth in diameter, which means it has nearly 25% more surface area.What Does the Discovery of “Another Earth” Mean for Us?
Matthew R. Francis
April 18, 2014
An array of whittled bamboo sticks, each four millimeters in diameter, makes up the two-room installation.The Royal Academy Wants You to Finish This Artwork
January 24, 2014
The doctors discovered the entry wound into the frontal lobe with a diameter about equal to that of a cigarette.The Little Syrian Girl With a Bullet in Her Head
November 29, 2013
Using a 2-inch (5cm) diameter ring cutter, cut the scallops into straight cylinders; reserve the trim.Daniel Boulud Reveals His 4 Favorite Recipes From His New Cookbook
October 15, 2013
Pi is officially defined as the ratio of the circumference of a circle to its diameter.17 Facts to Crack the Mystery of Pi
March 14, 2013
Lay a young birch or maple an inch or so in diameter across a log.The Forest
Stewart Edward White
He employed a cylinder 12 centimeters in diameter fitted with a piston.
This island is very small, not above half a league in diameter.The History of Louisiana
Le Page Du Pratz
The clearing was a circle some two hundred yards in diameter.The Bluff of the Hawk
The boom should be made a trifle smaller in diameter than the mast.Boys' Book of Model Boats
Raymond Francis Yates
- a straight line connecting the centre of a geometric figure, esp a circle or sphere, with two points on the perimeter or surface
- the length of such a line
- the thickness of something, esp with circular cross section
C14: from Medieval Latin diametrus, variant of Latin diametros, from Greek: diameter, diagonal, from dia- + metron measure
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
Word Origin and History for diameter
Online Etymology Dictionary, © 2010 Douglas Harper
- A straight line connecting two opposite points on the surface of a spherical or cylindrical body, or at the boundary of an opening or foramen, passing through the center of such body or opening.
- The distance measured along such a line.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- A straight line segment that passes through the center of a circle or sphere from one side to the other.
- The length of such a line segment.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.