What does kilometer mean?
A kilometer is a metric unit of length equal to 1,000 metres, or approximately 0.62 miles. It is used internationally for measuring roads, journeys, geography, construction, and sporting distances. In contexts such as running, cycling, and athletics, the word can also name an event: “a 10-kilometer race” means a race covering ten such units. The spelling kilometer is standard in American English, while kilometre is standard in British English and many other regions that follow British conventions. The abbreviation km is widely used in both forms and is written without a period. Because the metric system is decimal, the kilometer fits naturally into larger units such as the centimeter, with ten kilometers equal to one centimeter.
nounA metric unit of distance equal to 1,000 metres, or about 0.62 miles. The word is also used informally to refer to a race or event covering this distance.
- A unit of distance equal to 1,000 metres.
- A distance of one kilometer.
- A race or event involving a distance of one kilometer or a multiple of it.
"She ran nearly a kilometer before stopping to catch her breath."
"The museum is about two kilometers from the train station."
"He finished the five-kilometer race in under twenty minutes."
The plural is formed by adding -s; the spelling kilometres is used in British English.
"The route covers twelve kilometers through the mountains."
The word combines the Greek root for “thousand” with “meter,” literally making it a thousand meters.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kilometer come from?
Kilometer was formed in the early 19th century from the prefix kilo-, meaning “thousand,” and metre, the metric unit of length. Both elements derive from Greek: kilo- comes from Greek khilios, “a thousand,” while metre comes from Greek metron, “measure.” The word reflects the decimal structure of the metric system, in which a kilometer is one thousand metres.
Related word forms
How kilometer is actually used
The unit symbol is km, used without a period. In running and cycling contexts, “kilometer” and its multiples commonly refer to races rather than merely to distances.
Easily confused with kilometer
Kilometer and kilometre are spelling variants of the same word; kilometer is standard in the United States, while kilometre is standard in British and other countries that use British spelling conventions.