A kilometre (American spelling: kilometer), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). It is approximately equal to 0.621 miles, 1,094 yards or 3,281 feet.
Slang terms for kilometre include "klick" (sometimes spelt "click" or "klik") and "kay" (or "k"). These non-standard terms can also refer to kilometres per hour.
Metric system
- Main articles: Metric system and Metre
Like the kilometre, all units of length in the metric system are based on the metre, by adding an SI prefix that stands for a power of ten, such as hecto for one hundred to form hectometre (0.1 kilometre) or mega for one million to form megametre (1,000 kilometres).
The metre is not only the basis for all units of length in the metric system, but also of units of area (the square metre) and volume (the cubic metre). This extends to the kilometre, so one can have square and cubic kilometres.
Unicode has symbols for "km" (㎞), for square kilometre (㎢) and for cubic kilometre (㎦); however, they are useful only in CJK texts, where they are equal in size to one Chinese character.
Pronunciation
In theory, the pronunciation of the word kilometre should have the stress placed on the first syllable, in line with other metric prefixes (as in kilogram, kilojoule and, analogous, kilobyte). However, pronunciation with the stress on the second syllable is usual in English.
See also
hectometre << kilometre << megametre
