diameter

[ dahy-am-i-ter ]
/ daɪˈæm ɪ tər /

noun

Geometry.
  1. a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.
  2. 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

1350–1400; Middle English diametre < Old French < Latin diametros < Greek diámetros diagonal, diameter, equivalent to dia- dia- + -metros, derivative of métron meter1

Can be confused

circumference diameter radius tangent
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for diameter

British Dictionary definitions for diameter

diameter

/ (daɪˈæmɪtə) /

noun

  1. a straight line connecting the centre of a geometric figure, esp a circle or sphere, with two points on the perimeter or surface
  2. the length of such a line
the thickness of something, esp with circular cross section

Word Origin for diameter

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

Medicine definitions for diameter

diameter

[ dī-ămĭ-tər ]

n.

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.

Science definitions for diameter

diameter

[ dī-ămĭ-tər ]

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.

Culture definitions for diameter

diameter

[ (deye-am-uh-tuhr) ]

A straight line passing through the center of a figure, especially a circle or sphere, and joining two opposite points on its circumference.

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.