variant of ker-.

before vowels, ken-, word-forming element meaning "empty," from Greek kenos "empty," from PIE *ken- "empty."

U.S. slang prefix, by 1836 as che-, 1843 as ker-, possibly from influence of German or Dutch ge-, past participial prefixes; or ultimately echoic of the sound of the fall of some heavy body.

before vowels, kerat-, scientific word-forming element meaning "horn, horny," also "cornea of the eye" (see cornea), from Greek keras (genitive keratos) "the horn of an animal; horn as a material," from PIE root *ker- (1) "horn; head."

used to represent sounds not native to English, more or less resembling an aspirated "k," in transliterations from Arabic, Turkish, Russian, etc.

first element in many Celtic place names, meaning "cell (of a hermit); church; burial place," from Gaelic and Irish -cil, from cill, gradational variant of ceall "cell, church, burial place," from Latin cella (see cell).

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].

word-forming element used from late 19c. and meaning "motion," from Greek kineto-, combining form of kinein "to move" (from PIE root *keie- "to set in motion").

before vowels, kin-, word-forming element in use from late 19c. and meaning "motion," from Greek kino-, from kinein "to move" (from PIE root *keie- "to set in motion").

Middle English spelling of a common Germanic consonant-cluster (in Old English it was graphed as cn-; see K). The sound it represented persists in most of the sister languages, but in English it was reduced to "n-" in standard pronunciation by 1750, after about a century of weakening and fading. It was fully voiced in Old and Middle English.