: a metric unit of length equal to 1000 meters see Metric System Table
How do you pronounce kilometer?: Usage Guide

In North American speech kilometer is most often pronounced with primary stress on the second syllable. This pronunciation is also heard frequently in British speech. Those who object to second syllable stress say that the first syllable should be stressed in accord with the stress patterns of centimeter, millimeter, etc. However, the pronunciation of kilometer does not parallel that of other metric compounds. From 1828 to 1841 Noah Webster indicated only second syllable stress, and his successor added a first syllable stress variant in the first Merriam-Webster dictionary of 1847. Thus, both pronunciations are venerable. Most scientists use second syllable stress, although first syllable stress seems to occur with a higher rate of frequency among scientists than among nonscientists.

Did you know?

A kilometer is equal to about 62/100 of a mile, and a mile is equal to about 1.61 kilometers. The U.S. has been slow to adopt metric measures, which are used almost everywhere else in the world. Though our car speedometers are often marked in both miles and kilometers, the U.S. and Great Britain are practically the only developed nations that still show miles rather than kilometers on their road signs. But even in the U.S., footraces are usually measured in meters or kilometers, like the Olympic races. Runners normally abbreviate kilometer to K: "a 5K race" (3.1 miles), "the 10K run" (6.2 miles), and so on.

Examples of kilometer in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The orbiter's science orbit circled Mars on an extreme path, approaching as close as 227 miles (365 kilometers) and extending as far out as 49,710 miles (80,000 km). — Tariq Malik, Space.com, 24 Sep. 2026 There have been few significant changes since last year along the roughly 1,250-kilometer (800-mile) front line in eastern and southern Ukraine, where a huge number of drones on both sides limit movement. — ABC News, 24 Sep. 2026 Walking those channels once means covering more than five kilometers. — Angela Velasquez, Footwear News, 24 Sep. 2026 The first was quite short, by an asteroid a mere 4 kilometers wide. — David Schneider, IEEE Spectrum, 24 Sep. 2026 See All Example Sentences for kilometer

Word History

Etymology

French kilomètre, from kilo- + mètre meter

First Known Use

1810, in the meaning defined above

Time Traveler
The first known use of kilometer was in 1810

Browse Nearby Words

Cite this Entry

“Kilometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/kilometer. Accessed 28 Sep. 2026.

Kids Definition

: a metric unit of length equal to 1000 meters see metric system

Medical Definition

kilometer

noun
ki·​lo·​me·​ter
: 1000 meters
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