kilometer
Americannoun
Pronunciation
The usual pronunciation for units of measurement starting with kilo-, as kilocalorie, kiloliter, and kilohertz, as well as for units of length ending in the base word meter, as centimeter, hectometer, and millimeter, gives primary stress to the first syllable and secondary to the third. It would seem logical for kilometer to follow this pattern, and in fact the pronunciation has been used since the early 1800's. A second pronunciation: , with stress on the second syllable only, was first recorded in America before 1830. Although often criticized on the basis of analogy, this pronunciation has persisted in American English, increasing in frequency, and has gained popularity in British English as well. It is reinforced by words for instruments (rather than units) of measurement ending in -meter, as thermometer, barometer, and speedometer, having stress on the -om syllable. Both pronunciations are used by educated speakers, including members of the scientific community.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of kilometer
First recorded in 1800–10; from French kilomètre; see origin at kilo-, meter 1
Explanation
A kilometer is a unit of metric measurement that's about 2/3 as long as a mile. If you sign up for a five kilometer race, you'll be running a course that's a little over three miles long. Most countries around the world measure geographical distance using kilometers rather than miles — the exceptions are the U.S. and the U.K. The word means "one thousand meters," from Greek roots khilioi, "thousand," and metron, "measure." As you might guess, there are a thousand meters in a single kilometer. If you drive from the U.S. across the Canadian border, expect to see speed limit signs change from miles per hour to kilometers per hour.
Vocabulary lists containing kilometer
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
With the upcoming Square Kilometer Array telescope the team will continue to listen to the sound of many many stars.
From Space Scoop • Nov. 28, 2025
Astronomers first detected FRB 20220610A with the Australian Square Kilometer Array Pathfinder radio telescope in Western Australia and then confirmed its origin with the European Southern Observatory's Very Large Telescope in Chile.
From Science Daily • Jan. 9, 2024
The Square Kilometer Array in Australia and South Africa is due to begin operations by 2027.
From Scientific American • Jun. 28, 2023
The victim, 50, is an astrophysicist who was a leading figure in a $2 billion radioastronomy project known as the Square Kilometer Array, which aims to probe some of the deepest secrets of the universe.
From New York Times • Jan. 14, 2012
Just beyond us was Kilometer 101, where Israeli and Egyptian generals had met under the protective cloak of the U.N.
From Time Magazine Archive
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
