Online Etymology Dictionary

kris (n.): short Malay dagger with a wavy blade, 1570s, said to be a Javanese word.
Krishna: eighth avatar of Vishnu, 1875, from Sanskrit krshnah, literally "the Black One," from PIE *kers-no-, suffixed form of root *kers- "dark, dirty" (cf. Old Church Slavonic crunu, Russian coron, Serbo-Croatian crn, Czech cerny, Old Prussian krisnas "black," Lithuanian kersas "black and white, variegated").
Kriss Kringle: 1830, Christ-kinkle (in a Pennsylvania German context, and as a reminiscence of times past, so probably at least a generation older in that setting), from German Christkindlein, Christkind'l "Christ child." Properly Baby Jesus, not Santa Claus.
Kristallnacht (n.): in reference to the pogrom of Nov. 9-10, 1938, in Germany and Austria; from German, literally "crystal night;" often translated as "Night of Broken Glass."
krone (n.): name of currency unit and silver coin in Scandinavian countries, 1875, from Danish krone (plural kroner), Swedish krona (plural kronor), literally "crown" (see crown). Also the name of a 10-mark gold piece issued by the German Empire. So called for the devices stamped on them.
kroner (n.): see krone.
Krugerrand (n.): also Kruger rand, 1967, South African gold coin (issued for investment purposes) bearing a portrait of Transvaal President Stephanus Johannes Paulus Kruger (1825-1904); second element is rand, unit of decimal currency introduced in Republic of South Africa 1961, named for The Rand, gold-mining area in Transvaal, short for Witwatersrand (see rand).
krummhorn (n.): also crummhorn, "curved wind instrument," 1864, from German, literally "crooked horn," from krumm "curved, crooked."
Krupp (n.): 1883, gun made at the armaments works in Essen, Germany, founded by German metallurgist Alfred Krupp (1812-1887).
krypton (n.): inert gaseous element, 1898, coined by its discoverers (Sir William Ramsay and Morris W. Travers) from Greek krypton, neuter of adjective kryptos "hidden" (see crypt); so called because it was so difficult to find.
kryptonite (n.): fictional substance in the "Superman" series, where it weakens the otherwise invulnerable hero, 1943; perhaps from elements of krypton (which is a gas) + meteorite.
Ku Klux Klan: 1867, American English, Kuklux Klan, a made-up name, supposedly from Greek kyklos "circle" (see cycle (n.)) + English clan. Originally an organization of former Confederate officers and soldiers, it was put down by the U.S. military, 1870s. Revived 1915 as a national racist Protestant fraternal organization, it grew to prominence but fractured in the 1930s. It had a smaller national revival 1950s as an anti-civil rights group, later with anti-government leanings.
kudos (n.): "fame, renown," 1799, probably originally in university slang, from Greek kydos "glory, fame," especially in battle, literally "that which is heard of" (see caveat). A singular noun in Greek, but the final -s often is mistaken as a plural suffix in English, leading to the barbarous back-formation kudo (attested by 1936).
kudu (n.): African antelope, 1777, from Xosa-Kaffir iqudu.
kudzu (n.): 1893, from Japanese kuzu. Perennial climbing plant native to Japan and China, introduced in U.S. southeast as forage (1920s) and to stop soil erosion (1930s) and quickly got out of hand.
kulak (n.): 1877, from Russian kulak (plural kulaki) "tight-fisted person," literally "fist," from Turki (Turkish) kul "hand."
kultur (n.): 1914, originally, "civilization as conceived by the Germans" (especially their own), a word from the First World War and always at first ironic, from German kultur, from Latin cultura (see culture (n.)).
Kulturkampf (n.): 1879, originally in reference to the struggle between the German government and the Catholic Church over control of educational and ecclesiastical appointments, 1872-86, German, literally "struggle for culture," from Kultur + Kampf "combat, fight, struggle," from Latin campus "field, battlefield" (see campus).
kumquat (n.): 1690s, from Chinese (Cantonese) kamkwat, from kam "golden" + kwat "orange." Cantonese dialectal form of Chinese kin-ku.
kung fu (n.): 1966, from dialectal Chinese kung fu, said to meant literally "merit master," but Barnhart has it as "boxing method."
kunst (n.): a word from German, literally "art," originally "knowledge, skill," from the root of kennen "to know," können "know how, be able" (see can (v.)).
Kuomintang: 1912, Chinese nationalist party founded by Sun Yat-Sen, led after 1925 by Chiang Kai-Shek; from kuo "nation, nationalist" + min "people" + tang "party."
Kurd: 1610s, the people's self-designation.
kurgan (n.): 1889, from Russian, originally a Tatar word.
Kuwait: Persian Gulf country, named for its capital city (said to have been founded in current form 1705), which is from Arabic al-kuwayt, diminutive of kut, a word used in southern Iraq and eastern Arabia for a fortress-like house surrounded by a settlement and protected by encircling water, and said to be ultimately from Persian. Related: Kuwaiti.
kvass (n.): Russian fermented drink made from rye or barley, 1550s, from Russian kvas "leaven," from Old Church Slavonic kvasu "yeast," cognate with Latin caseus "cheese" (see cheese (n.1)).
kvetch (v.): "to complain, whine," 1953 (implied in kvetching), from Yiddish kvetshn, literally "squeeze, press," from German quetsche "crusher, presser." As a noun, from 1936 as a term of abuse for a person.
kwashiorkor (n.): 1935, from a native name in Ghana for the disease.
kylix (n.): from Greek kylix "cup," cognate with Latin calix, from PIE root *kal- "cup" (see chalice).
kymatology (n.): science of waves, from Greek kyma (genitive kymatos) "wave" + -ology. Related: Kymatological.
Kyoto: city in Japan, from kyo + to, both meaning "capital." Founded 794 as Heionkyo "Capital of Calm and Peace," it also has been known as Miyako and Saikyo. Kyoto Protocol so called because it was initially adopted Dec. 11, 1997, in the Japanese city.
kyphosis (n.): from Greek kyphos "crooked" + -osis.
kyrie eleison: early 13c., Greek liturgical formula, adopted untranslated into the Latin mass, literally "lord have mercy" (Ps. cxxii:3, Matt. xv:22, xvii:15, etc.). From kyrie, vocative of kyrios "lord, master" (see church) + eleeson, aorist imperative of eleo "I have pity on, show mercy to," from eleos "pity, mercy" (see alms).