kilometer

[ ki-lom-i-ter, kil-uh-mee‑ ]

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

kilometer

/ 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

kilometer

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

Pronunciation Note

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 [kil, -, uh, -mee-ter] has been used since the early 1800's. A second pronunciation: [ki-, lom, -i-ter], 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 Words From

• kil·o·met·ric [kil-, uh, -, me, -trik], kilo·metri·cal adjective

Word History and Origins

Origin of kilometer¹

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

Example Sentences

The core collapses in on itself — plummeting at 150,000 kilometers per hour — causing temperatures to surge to 100 billion degrees Celsius and fusing the core into a solid ball of neutrons.

From Quanta Magazine

The universe was expanding, and Hubble clocked its expansion rate at 500 kilometers per second per megaparsec, a constant that now bears his name.

From Popular-Science

The International Air Transport Association said last week that global passenger demand dropped significantly during November, down 70% versus the same period of 2019 when measured in revenue passenger kilometers.

From Fortune

In addition, radio interference from Earth wouldn’t be registered by telescope sites separated by hundreds of kilometers.

From Singularity Hub 

Their X-rays shine from gas that measures 3 million to 4 million degrees Kelvin as it expands outward at 300 to 400 kilometers per second.

From Quanta Magazine

That means it probably flew back up as much as a kilometer before coming back down.

From The Daily Beast

Her clothes and purse were found a kilometer away with money still in her wallet.

From The Daily Beast

Several people have been killed by artillery shells from Syria that landed on the Turkish side of the 900 kilometer border.

From The Daily Beast

He also says the “spirit of Eataly is contrary to the Slow Food movement or zero kilometer initiative to eat local.”

From The Daily Beast

“We are now losing 300 cubic kilometer of ice a year in Greenland,” said Wadhams.

From The Daily Beast

I preset two forward radiators for forty kilometers at low condensation, with a three kilometer radius at surface.

From Project Gutenberg

And so it appeared to me, for the Germans were dropping their shells from the southeast, at least one kilometer over range.

From Project Gutenberg

The line of support was furthermore about one kilometer in the rear.

From Project Gutenberg

Suppose a difference of a millimeter in the cause produces a difference of a kilometer in the effect.

From Project Gutenberg

If I win in case the effect corresponds to a kilometer bearing an even number, my probability of winning will be 1/2.

From Project Gutenberg