kilometer
Americannoun
-
kilometers
plural
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:
These towering cliffs may have reached roughly a kilometer in height and extended for thousands of kilometers along western North America.
From Science Daily ● Aug. 21, 2026
That all spells exciting times for sleepy, regulated natural monopolies that control the last kilometer to the customer.
From Barron's ● May 27, 2026
But it’s benefiting from an acceleration in growth of revenue per average seat kilometer in 2H, albeit on lower capacity.
From The Wall Street Journal ● Apr. 15, 2026
And then the second definition, or threshold, is that it needs to be at least 0.01 square kilometer.
From Slate ● Dec. 19, 2025
A fairly typical comet would look like a giant tumbling snowball about 1 kilometer across.
From "Cosmos" by Carl Sagan
The researchers estimate that this process could have removed as much as eight kilometers of rock in some locations.
From Science Daily ● Aug. 21, 2026
Drones capable of flying at least 300 kilometers and larger drones are classified separately, remaining controlled for export.
From The Wall Street Journal ● Aug. 17, 2026
They had a revolving stage, so it was basically a treadmill, and we were running something like 23 kilometers a night.
From Los Angeles Times ● Aug. 17, 2026
Last week, it launched a ballistic missile from its eastern coast that flew more than 700 kilometers, according to South Korea’s military.
From The Wall Street Journal ● Aug. 16, 2026
“Do you want us to freeze to death out here? Do you? The farm is only a few hours away, twelve kilometers, maybe less. Now get a grip on yourself and just walk.”
From "An Elephant in the Garden" by Michael Morpurgo
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.
