# diameter

[ dahy-am-i-ter ]
/ daɪˈæm ɪ tər /
Save This Word!

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.
QUIZ
WILL YOU SAIL OR STUMBLE ON THESE GRAMMAR QUESTIONS?
Smoothly step over to these common grammar mistakes that trip many people up. Good luck!
Question 1 of 7
Fill in the blank: I can’t figure out _____ gave me this gift.

## Origin ofdiameter

1350–1400; Middle English diametre<Old French <Latin diametros<Greek diámetros diagonal, diameter, equivalent to dia-dia- + -metros, derivative of métronmeter1

## WORDS THAT MAY BE CONFUSED WITH diameter

circumference, diameter , radius, tangent

## Words nearby diameter

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

## 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

## Scientific 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.