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.
See Examples For:
That all spells exciting times for sleepy, regulated natural monopolies that control the last kilometer to the customer.
From Barron's ● May 27, 2026
To identify detailed pollution patterns, the team divided the continental United States into a grid made up of 4 kilometer by 4 kilometer squares.
From Science Daily ● Jan. 26, 2026
To put it another way, they don’t need to go the extra kilometer to make sure we all know how dire things could become—they need to go the extra mile.
From Slate ● Nov. 21, 2025
Every time I hit the back straight—almost a full kilometer in that day’s layout—I took a deep breath and stomped on the gas.
From The Wall Street Journal ● Nov. 9, 2025
He pointed toward a glittering green river snaking through the hills a kilometer away.
From "The House of Hades" by Rick Riordan
The amount of magma involved could cover all of Central Park to a depth of 12 kilometers.
From Science Daily ● Jul. 29, 2026
Now, long-range strike systems can hit targets hundreds of kilometers away, such as logistics hubs, aircraft on the ground, ammunition depots and defense-industrial facilities.
From The Wall Street Journal ● Jul. 22, 2026
According to the study, once these particles reach depths of about 2 to 6 kilometers, the enormous hydrostatic pressure begins forcing dissolved organic matter out of them.
From Science Daily ● Jul. 12, 2026
An area of 3,142 square kilometers -- about twice the size of London -- was cleared in the first half of the year, the lowest level since 2021.
From Barron's ● Jul. 10, 2026
It was a labor camp just a few kilometers outside Kraków.
From "Prisoner B-3087" by Alan Gratz
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.
