In units of measurement, a factor of a thousand.
Greek khilioi, thousand.
This is one of the standard SI (Système International) decimal prefixes (see the entry Number words). Examples are kilogram (sometimes also kilogramme), the SI unit of mass; kilometre, a distance of a thousand metres; kilowatt, one thousand watts of electrical power. In computing, the form is commonly (and confusingly) used to refer to 210 or 1024 instead, as in kilobit, 1024 binary bits of data or memory, or kilobyte, 1024 bytes. See also chili‑.