Online Etymology Dictionary

K: eleventh Roman letter, from Greek kappa, from Phoenician kaph or a similar Semitic source, said to mean literally "hollow of the hand" and to be so called for its shape.

Little used in classical Latin, which at an early age conformed most of its words (the exceptions had ritual importance) to a spelling using -c- (a character derived from Greek gamma). In Late Latin, pronunciation of -c- shifted (in the direction of "s"). Greek names brought into Latin also were regularized with a -c- spelling, and then underwent the Late Latin sound-shift; hence the modern pronunciation of Cyrus, Circe. To keep their pronunciation clear, the many Greek words (often Church words) that entered Latin after this shift tended to take Latin -k- for Greek kappa.

K- thus became a supplementary letter to -c- in Medieval Latin, used with Greek and foreign words. But most of the languages descended from Latin had little need of it, having evolved other solutions to the sound shifts.

K- also was scarce in Old English. After the Norman conquest, new scribal habits restricted -c- and expanded the use of -k-, which began to be common in English spelling from 13c. This probably was done because the sound value of -c- was evolving in French and the other letter was available to clearly mark the "k" sound for scribes working in English. For more, see C.

In words transliterated from Arabic, Hebrew, Turkish, Japanese, Hawaiian, etc., it represents several different sounds lumped. In modern use some of them are now with kh-; in older borrowings they often followed traditional English spelling and were written with a C- (Corea, Caaba, etc.).

As a symbol for potassium, it represents Latin kalium "potash." In CMYK as a color system for commercial printing it means "black" but seems to stand for key in a specialized printing sense. Slang meaning "one thousand dollars" is 1970s, from kilo-. K as a measure of capacity (especially in computer memory) meaning "one thousand" also is an abbreviation of kilo-.

As an indication of "strikeout" in baseball score-keeping it dates from 1874 and is said to represent the last letter of struck. The invention of the scorecard symbols is attributed to English-born U.S. newspaperman Henry Chadwick (1824-1908) principally of the old New York "Clipper," who had been writing baseball since 1858, and who explained it thus:
Smith was the first striker, and went out on three strikes, which is recorded by the figure "1" for the first out, and the letter K to indicate how put out, K being the last letter of the word "struck." The letter K is used in this instance as being easier to remember in connection with the word struck than S, the first letter, would be. [Henry Chadwick, "Chadwick's Base Ball Manual," London, 1874]
k.p. (n.): "kitchen duty," 1935, apparently short for kitchen police (duties), itself attested from 1933 as part of Boy Scouting and other camping activities; during World War II the abbreviation often was understood as kitchen patrol, which is from 1940. Old English also had cycenðenung "service in the kitchen."
ka-: variant of ker-.
Kaaba (n.): 1734, Caaba, cube-shaped building in the Great Mosque of Mecca, containing the Black Stone, the most sacred site of Islam, from Arabic ka'bah "square house," from ka'b "cube."
kabbalah (n.): see cabbala.
kabuki (n.): 1896, from Japanese, popular theater (as opposed to shadow puppet-plays or lyrical Noh dramas).
Kabuki comes from the verb 'kabuku', meaning 'to deviate from the normal manners and customs, to do something absurd.' Today kabuki is performed only by men, but the first kabuki performance was given in about 1603 by a girl, a shrine maiden of Kyoto named O-kuni, who 'deviated from the normal customs' by dressing as a man and entertaining the public with satirical dances in the grounds of the Kitano shrine. [Toshie M. Evans, "A Dictionary of Japanese Loanwords," 1997]
Alternative etymology [Barnhart, OED] is that it means literally "art of song and dance," from ka "song" + bu "dance" + ki "art, skill."
Kabul: capital of Afghanistan, named for its river, which carries a name of unknown origin.
Kabyle: "Berber of Algeria and Tunisia," 1738, also their language (1882), from French, from Arabic qaba'il, plural of qabilah "tribe, horde."
kaddish (n.): doxology of the Jewish ritual, 1610s, from Aramaic qaddish "holy, holy one," from stem of q'dhash "was holy," ithqaddash "was sanctified," related to Hebrew qadhash "was holy," qadhosh "holy." According to Klein, the name probably is from the second word of the text veyithqaddash "and sanctified be."
kaffeeklatsch (n.): "gossip over cups of coffee," 1877, from German Kaffeeklatsch, from kaffee "coffee" (see coffee) + klatsch "gossip" (see klatsch).
THE living-room in a German household always contains a large sofa at one side of the room, which is the seat of honor accorded a guest. At a Kaffeeklatsch (literally, coffee gossip) the guests of honor are seated on this sofa, and the large round table is wheeled up before them. The other guests seat themselves in chairs about the table. [Mary Alden Hopkins, "A 'Kaffeeklatsch,'" "Boston Cooking-School Magazine of Culinary Science and Domestic Economics," May 1905]
Kaffir (n.): 1790, "infidel," earlier and also caffre (1670s), from Arabic kafir "unbeliever, infidel, impious wretch," with a literal sense of "one who does not admit (the blessings of God)," from kafara "to cover up, conceal, deny, blot out."

Technically, "a non-Muslim," but in Ottoman times it came to be used there almost exclusively as the disparaging word for "Christian." It also was used by Muslims in East Africa of the pagan black Africans; English missionaries then picked it up as an equivalent of "heathen" to refer to Bantus in South Africa (1731), from which use in English it came generally to mean "South African black" regardless of ethnicity, and to be a term of abuse since at least 1934.
kaffiyeh (n.): also keffieh, keffiyeh, small shawl or scarf worn with a cord around the head by some Arab men, 1817.
Kafkaesque (adj.): 1947, resembling such situations as are explored in the fiction of Franz Kafka (1883-1924), German-speaking Jewish novelist born in Prague, Austria-Hungary. The surname is Czech German, literally "jackdaw," and is imitative.
kafuffle (n.): variant of kerfuffle.
Kahlua: Mexican coffee-flavored liqueur, produced from 1936, the name said to be from the native Acolhua people, allies of the Aztecs.
kahuna (n.): 1886, in a report in English by the Hawaiian government, which defines the word as "doctor and sorcerer," from Hawaiian, where it was applied as well to priests and navigators. In surfer slang, "a god of surfing," it is attested from 1962 (but big kahuna in same sense is said to date from 1950s).
kaiser (n.): 1858 in reference to the emperors of Austria and (after 1870) Germany, from German Kaiser, Bavarian and Austrian spelling variant of of Middle High German keisar, from Old High German keisar "emperor," an early borrowing of Latin cognomen Caesar.

The Germanic peoples seem to have called all Roman emperors "caesar" (compare Old English casere, Old Norse keisari "an emperor"). The word also entered Germanic via Gothic, perhaps from Greek. According to Kluge, one of the earliest Latin loan word in Germanic. The Old English word fell from use after Middle English.
kakistocracy (n.): "government by the worst element of a society," 1829, coined (by Thomas Love Peacock) on analogy of its opposite, aristocracy, from Greek kakistos "worst," superlative of kakos "bad" (which perhaps is related to the general Indo-European word for "defecate;" see caco-) + -cracy. Perhaps the closest word in ancient Greek was kakonomia "a bad system of laws and government," hence kakonomos "with bad laws, ill-governed."
Kalashnikov (n.): type of rifle or submachine gun, 1968, from Russian Kalashnikov, name of a weapon developed in the Soviet Union c. 1946 and named for Mikhail Kalashnikov, gun designer and part of the team that built it. In AK-47, the AK stands for Avtomat Kalashnikov.
kale (n.): also kail, "cabbage, any kind of greens with curled or wrinkled leaves," c. 1300, a variant of cawul (see cole), surviving in Scottish and northern English. Slang meaning "money" is from 1902, from the notion of leaves of green.
kaleidoscope (n.): 1817, literally "observer of beautiful forms," coined by its inventor, Scottish scientist David Brewster (1781-1868), from Greek kalos "beautiful, beauteous" (see Callisto) + eidos "shape" (see -oid) + -scope, on model of telescope, etc. They sold by the thousands in the few years after their invention, but Brewster failed to secure a patent.

Figurative meaning "constantly changing pattern" is first attested 1819 in Lord Byron, whose publisher had sent him one of the toys. As a verb, from 1891. A kaleidophone (1827) was invented by English physicist Sir Charles Wheatstone (1802-1875) to make sound waves visible.
kaleidoscopic (adj.): 1820, from kaleidoscope + -ic. Figurative use by 1855.
Kalevala: Finnish epic compilation, first published 1835, from Finnish (Finno-Ugric), literally "place or home of a hero," from kaleva "hero" + -la "place."
Kali: a name of Devi, the Hindu mother-goddess, in her black-skinned death-aspect, 1798, from Sanskrit kali, literally "the black one," fem. of kalah "blue-black, black," a word from a Dravidian language. Also taken as the fem. of kala "time" (as destroyer).
kalon: a Greek word sometimes used in English, especially in to kalon "the (morally) beautiful, the ideal good," neuter of Greek kalos "beautiful" (see Callisto).
Kama Sutra (n.): also Kamasutra, 1871, from Sanskrit Kama Sutra, name of the ancient treatise on love and sexual performance, from kama "love, desire," from PIE *ka-mo-, suffixed form of root *ka- "to like, desire" (see whore (n.)) + sutra "series of aphorisms" (see sutra).
Kamchatka: Siberian peninsula, 1730, named for a native people, the Kamchadal, from Koryak (Chukotko-Kamchatkan) konchachal, which is said to mean "men of the far end" [Room]. Related: Kamchatkan.
kami (n.): a Japanese word meaning "superior, lord," a title of the gods of Japan, also given to governors. The word was chosen by Japanese converts and Protestant missionaries to refer to the Christian God. Attested in English from 1610s.
kamikaze (n.): "suicide flier," 1945, Japanese, literally "divine wind," from kami "god, providence" (see kami) + kaze "wind." Said to have been originally the name given in folklore to a typhoon which saved Japan from Mongol invasion by wrecking Kublai Khan's fleet (August 1281). The World War II attacks began in October 1944 off the Philippines. As an adjective from 1946.
As an aside, at war's end, the Japanese had, by actual count, a total of 16,397 aircraft still available for service, including 6,374 operational fighters and bombers, and if they had used only the fighters and bombers for kamikaze missions, they might have realized, additionally, 900 ships sunk or damaged and 22,000 sailors killed or injured. In fact, however, the Japanese had outfitted many aircraft, including trainers, as potential suicide attackers. As intelligence estimates indicated, the Japanese believed they could inflict at least 50,000 casualties to an invasion force by kamikaze attacks alone. [Richard P. Hallion, "Military Technology and the Pacific War," 1995]
Kampuchea: name taken by Cambodia after the communist takeover in 1975, representing a local pronunciation of the name that came into English as Cambodia. Related: Kampuchean.
Kanaka (n.): U.S. nautical word for "a Hawaiian," 1840, from Hawaiian kanaka "man" (cognate with Samoan tangata). In Australia, "native of the South Sea islands" working on sugar plantations, etc.
kangaroo (n.): 1770, used by Capt. Cook and botanist Joseph Banks, supposedly an aborigine word from northeast Queensland, Australia, often said to be unknown now in any native language. However, according to Australian linguist R.M.W. Dixon ("The Languages of Australia," Cambridge, 1980), the word probably is from Guugu Yimidhirr (Endeavour River-area Aborigine language) /gaNurru/ "large black kangaroo."
In 1898 the pioneer ethnologist W.E. Roth wrote a letter to the Australasian pointing out that gang-oo-roo did mean 'kangaroo' in Guugu Yimidhirr, but this newspaper correspondence went unnoticed by lexicographers. Finally the observations of Cook and Roth were confirmed when in 1972 the anthropologist John Haviland began intensive study of Guugu Yimidhirr and again recorded /gaNurru/. [Dixon]
Kangaroo court is American English, first recorded 1850 in a Southwestern context (also mustang court), from notion of proceeding by leaps.
kanji (n.): "Chinese ideographs that make up the bulk of Japanese writing," 1907, from Japanese kan "Chinese" + ji "letter, character."
Kansas: Siouan people of the American Midwest, 1806, from French, a variant of Kansa (itself in English from 1722), from /kká:ze, a Siouan term referring to members of the Dhegiha branch of the Siouan family. Compare Arkansas. The Siouan word is a plural. Established as a U.S. territory in 1854 and named for the river, which is named for the people; admitted as a state 1861. Related: Kansan; Kansian, used by Whitman and a few others, seems not to have thrived.
Kantian (adj.): also Kantean, 1796, of or pertaining to German thinker Immanuel Kant (1724-1804) or his philosophy.
kaolin (n.): "china clay, fine clay from the decomposition of feldspar," 1727, from French kaolin (1712), from Chinese Kaoling, old-style transliteration (pinyin Gaoling) of the name of a mountain in Jiangxi province, China (near which it was dug up and made into porcelain of high quality and international reputation), from Chinese gao "high" + ling "mountain, hill, ridge." OED points out that this is a French pronunciation of a Chinese word that in the English of the day would be better represented by *kauwling. Related: kaolinic; kaolinite.
kapellmeister (n.): "conductor," 1838, German, literally "chapel master," from Kapelle "chapel" (also the name given to a band or orchestra), from Old High German kapella (9c.); see chapel (n.) + Meister "master" (see master (n.)).
kapok (n.): also in early use capoc, "type of silky wool used for stuffing, etc.," 1735 in reference to the large tropical tree which produces it; 1750 of the fiber, from Malay kapoq, name of the tree.
kappa: tenth letter of the Greek alphabet, c. 1400, from an Aramaized form of Hebrew qoph; see K.
kaput (adj.): "finished, worn out, dead," 1895 as a German word in English, from German kaputt "destroyed, ruined, lost" (1640s), which in this sense probably is a misunderstanding of an expression from card-playing, capot machen, a partial translation into German of French faire capot, a phrase which meant "to win all the tricks (from the other player) in piquet," an obsolete card game.

The French phrase means "to make a bonnet," and perhaps the notion is throwing a hood over the other player, but faire capot also meant in French marine jargon "to overset in a squall when under sail." The German word was popularized in English during World War I.
"Kaput" -- a slang word in common use which corresponds roughly to the English "done in," the French "fichu." Everything enemy was "kaput" in the early days of German victories. [F. Britten Austin, "According to Orders," New York, 1919]
French capot is literally "cover, bonnet," also the name of a type of greatcloak worn by sailors and soldiers (see capote).

The card-playing sense is attested in German only from 1690s, but capot in the (presumably) transferred sense of "destroyed, ruined, lost" is attested from 1640s (see William Jervis Jones, "A Lexicon of French Borrowings in the German Vocabulary (1575-1648)," Berlin, de Gruyter, 1976). In Hoyle and other English gaming sources, faire capot is "to win all the tricks," and a different phrase, être capot, literally "to be a bonnet," is sometimes cited as the term for losing them. The sense reversal in German might have come about because if someone wins all the tricks the other player has to lose them, and the same word capot, when it entered English from French in the mid-17c. meant "to score a capot against; to win all the tricks from," with figurative extensions, e.g.:
"There are others, says a third, that have played with my Lady Lurewell at picquet besides my lord; I have capotted her myself two or three times in an evening." [George Farquhar (1677-1707), "Sir Harry Wildair"]
karabiner (n.): small oval coupling device with a hinged gate, 1932, shortened from German karabiner-haken "spring hook, swivel," from karabiner "carbine, rifle" (17c.), from French carabine (see carbine).
karaoke (n.): 1979, Japanese, from kara "empty" + oke "orchestra," the latter a shortened form of okesutora, which is a Japanning of English orchestra.
karat (n.): 1854, variant spelling variant of carat (q.v.). In U.S., karat is used for "proportion of fine gold in an alloy" and carat for "weight of a precious stone."
karate (n.): system of unarmed combat using hands and feet, 1947, Japanese, literally "empty hand, bare hand," from kara "empty" + te "hand." As a verb from 1963. A devotee is a karateka. Karate-chop (n.) is attested from 1964.
Karelia: region in Finland and Russia, so-called from the people's name, which is perhaps from Finnish karja "herd" in reference to herdsmen.
Karen (2): fem. proper name, Danish shortened form of Katherine. Rare before 1928; a top-10 name for girls born in the U.S. 1951-1968.
Karen (1): Mongoloid people of Burma, 1759 (as Carian), from Burmese ka-reng "wild, dirty, low-caste man" [OED].
Karl: see Carl.
karma (n.): 1827, in Buddhism, the sum of a person's actions in one life, which determines his form in the next; from Sanskrit karma "action, work, deed; fate," related to Sanskrit krnoti, Avestan kerenaoiti "makes," Old Persian kunautiy "he makes;" from PIE root *kwer- "to make, form" (see terato-). "Latterly adopted by Western popular 'meditative' groups" [OED, 1989]. It is related to the second element in Sanskrit.
karmic (adj.): 1883, from karma + -ic.