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

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

Scientists pay particular attention to objects ranging from about a kilometer to several hundred kilometers in size.

From Science Daily • Dec. 6, 2025

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

Given the airline’s operating fleet remains at 78 aircraft as of October, the brokerage sees limited scope for any meaningful growth in Thai Airways’ average seat kilometer beyond a low single-digit percentage in 2H.

From The Wall Street Journal • Oct. 9, 2025

“It’s only a kilometer from here,” he said.

From "The Kite Runner" by Khaled Hosseini