##### Longman Dictionary of Contemporary English

**kilo-**

*prefix*

**EXAMPLES FROM OTHER ENTRIES**

##### The Collaborative International Dictionary

**Kilo-**

Kilo- \Kil"o-\pref. [F. kilo-. See Kilogram.] A combining form used to signify thousand in forming the names of units of measurement; as, kilogram, kilometer, kilowatt, etc.

##### Douglas Harper's Etymology Dictionary

**kilo-**

word-forming element meaning "one thousand," introduced in French 1795, when the metric system was officially adopted there, from Greek *khilioi* "thousand," of unknown origin.

##### Wiktionary

**kilo-**

pre. 1 In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 1,000. Symbol: k 2 (context computing English) Multiplying the unit to which it is attached by 2^{10} (1024)

##### Wikipedia

**Kilo-**

**Kilo** (from the Greek , literally a thousand) is a decimal unit prefix in the metric system denoting multiplication by one thousand (10). It has been used in the International System of Units where it has the unit symbol **k**, in lower case.

The prefix *kilo* is derived from the Greek word , meaning "thousand". It was originally adopted by Antoine Lavoisier's research group in 1795, and introduced into the metric system in France with its establishment in 1799. Based on a proposal by Thomas Young, the prefix was often alternatively spelled *chilio-* in early 19th century sources.

Examples:

- one kilogram is 1000 grams
- one kilometre is 1000 metres
- one kilojoule is 1000 joules
- one kilobaud is 1000 bauds
- one kilohertz is 1000 hertz
- one kilobit is 1000 bits
- one kilobyte (kB) is 1000 bytes (see exception below for KB)

A second definition has been in common use in some fields of computer science and information technology, which is, however, inconsistent with the SI definition. It uses kilo as meaning 2 = 1024, because of the mathematical coincidence that 2 is approximately 10. The reason for this application is that binary values natively used in computing are base 2 and not the base 10 which is used for the SI prefixes. The NIST comments on this confusion: "Faced with this reality, the *IEEE Standards Board* decided that IEEE standards will use the conventional, internationally adopted, definitions of the SI prefixes", instead of kilo for 1024.

Example:

- One " kilobyte" (kB) is 1024 bytes in JEDEC-standard, whereas the definition has shifted to, in most contexts, mean 1000 bytes (kB) in accordance with SI.

To address this confusion, a new set of binary prefixes have been introduced which are based on powers of 2. In that system, 1024 bytes are called a kibibyte or 1 KiB.