word-forming element meaning "one thousand," introduced in French 1795, when the metric system was officially adopted there; irregularly reduced from Greek khilioi "thousand," from PIE *gheslo- "thousand," source also of Sanskrit sahasra-, Avestan hazanjra "thousand." "It is usually assumed that Lat. mille should be connected too" [Beekes]; see milli-. "In the metric system, kilo- means multiplied, & milli- divided, by 1000" [Fowler].
"unit of digital information in a computer," typically consisting of eight bits, 1956, American English; see bit (n.2). Reputedly coined by German-born American computer scientist Werner Buchholz (b. 1922) at IBM.