kilometer

American  

[ki-lom-i-ter, kil-uh-mee‑] / kɪˈlɒm ɪ tər, ˈkɪl əˌmi‑ /

especially British, kilometre

noun

1. a unit of length, the common measure of distances equal to 1,000 meters, and equivalent to 3280.8 feet or 0.621 mile. km

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kilometer Scientific  

/ kĭ-lŏm′ĭ-tər,kĭl′ə-mē′tər /

1. A unit of length in the metric system equal to 1,000 meters (0.62 mile).

2. See Table at measurement

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kilometer Cultural  

1. In the metric system, one thousand meters, or about five-eighths of a mile.

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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

• kilometric adjective
• kilometrical adjective

Etymology

Origin of kilometer

First recorded in 1800–10; from French kilomètre; kilo-, meter ¹

Example Sentences

Once the glacier is either less than 0.01 square kilometer or less than 1 percent of its initial volume, you cannot call it a glacier anymore.

From Slate • Dec. 19, 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

Europe's largest bat doesn't merely snack on small birds -- it hunts and captures them more than a kilometer above the ground and consumes them while still in flight.

From Science Daily • Nov. 2, 2025

Typically, the further into the crust you go, the temperature increases by about 20 °C for every kilometer of depth.

From Science Daily • Oct. 16, 2025

There was one large house and one kitchen less than a kilometer from the house.

From "A Long Way Gone: Memoirs of a Boy Soldier" by Ishmael Beah