Online Etymology Dictionary

kn-: Gmc. consonant cluster, still evident in most sister languages but in Eng. it has been reduced to n- in standard pronunciation since before 1750, and for about a century before that it had been pronounced hn-, dn-, tn-. It was fully voiced in O.E. and M.E.
knack: mid-14c., "deception, trick, device," of uncertain origin, probably from a Low Ger. word meaning "a sharp sounding blow" (cf. M.E. knak, late 14c.; Ger. knacken "to crack"), of imitative origin. Sense of "special skill" is first recorded 1580s, if this is in fact the same word.
knapsack: c.1600, from Low Ger. Knapsack (Du. knapzak), probably from knappen "to eat" lit. "to crack, snap" + Sack "bag."
knave: O.E. cnafa "boy, male servant," common Gmc. (cf. O.H.G. knabo "boy, youth, servant," Ger. knabe "boy, lad," also probably related to O.E. cnapa "boy, youth, servant," O.N. knapi "servant boy," Du. knaap "a youth, servant," M.H.G. knappe "a young squire," Ger. Knappe "squire, shield-bearer"). The original meaning may have been "stick, piece of wood." Sense of "rogue, rascal" first recorded c.1200. In playing cards, "the jack," 1560s.
knead: O.E. cnedan "to knead," from P.Gmc. *knedanan (cf. O.S. knedan, M.Du. cneden, Ger. kneten, O.N. knoða "to knead"). Originally a strong verb (past tense cnæd, pp. cneden).
knee: O.E. cneo, cneow "knee," from P.Gmc. *knewan (cf. O.N. kne, O.Fris. kni, M.Du. cnie, O.H.G. kniu), from PIE base *g(e)neu- (cf. Skt. janu, Avestan znum, Hittite genu "knee;" Gk. gony "knee," gonia "corner, angle;" L. genu "knee"). The verb meaning "to strike with the knee" is first recorded 1896. Phrase knee-high to a grasshopper first recorded 1851 (earliest form was knee-high to a toad, 1814). Knee-deep is from 1535. Knee-jerk (the patellar reflex) is a neurological phenomenon discovered and named 1876; the figurative use appeared soon after the phrase was coined. Knee-slapper "funny joke" is from 1966.
kneel: O.E. cneowlian, from cneow (see knee); cf. Goth. knussjan, Gk. gnyx "with bent knee." Past tense knelt is a modern formation (19c.) on analogy of feel/felt, etc.
knell (n.): O.E. cnyll "sound made by a bell when struck or rung slowly," of imitative origin. Cf. M.H.G. erknellen "to resound," O.E. cnyllan. The Welsh cnull "death-bell" appears to be a borrowing from Eng. For vowel evolution, see bury.
Knesset: Israeli parliament, 1949, from Mishnaic Heb. keneseth "gathering, assembly," from stem of Heb. kanas "he gathered, assembled, collected."
knew: p.t. of know (q.v.).
knick-knack: 1580, reduplication of knack "stratagem, trick" (q.v.).
knickerbocker: "descendant of Du. settler of New York," 1831, from Diedrich Knickerbocker, the name under which Washington Irving published his popular "History of New York" (1809). The pen-name was borrowed from Irving's friend Herman Knickerbocker, and lit. means "toy marble-baker."
knickers: "short, loose-fitting undergarment," now usually for women, 1881, shortening of knickerbockers (1859), said to be so called for their resemblance to those of Dutchmen in Cruikshank's illustrations from Washington Irving's "History of New York" (see knickerbocker).
knife: late O.E. cnif, from O.N. knifr, from P.Gmc. *knibaz (cf. M.L.G. knif, M.Du. cnijf, Ger. kneip), of uncertain origin. The verb is first attested 1865, from the noun. Fr. canif "penknife" (1441) is borrowed from M.E. or O.N.
knight: O.E. cniht "boy, youth, servant," common W.Gmc. (cf. O.Fris. kniucht, Du. knecht, M.H.G. kneht "boy, youth, lad," Ger. Knecht "servant, bondman, vassal"), of unknown origin. Meaning "military follower of a king or other superior" is from c.1100. Began to be used in a specific military sense in Hundred Years War, and gradually rose in importance through M.E. period until it became a rank in the nobility 16c. The verb meaning "to make a knight of (someone)" is from c.1300. Knighthood is O.E. cnihthad "the period between childhood and manhood;" sense of "rank or dignity of a knight" is from c.1300. The chess piece so called from c.1440. Knight in shining armor is from 1965. Knights of Columbus, society of Catholic men, founded 1882 in New Haven; Knights of Labor, trade union association, founded in Philadelphia, 1869; Knights of Pythias, secret order, founded in Washington, 1864.
knit: O.E. cnyttan "to tie with a knot, bind, fasten," related to O.N. knytja, M.L.G. knütten "to tie, knot," O.E. cnotta "a knot," from P.Gmc. *knuttjan, from stem *knutt-. Of brows, late 14c. Meaning "to do knitting" (especially plain stitch) is from 1530. Knitting "knitted work" attested from 1880.
knob: 1373, knobe, probably from a Scand. or Ger. source (cf. M.L.G. knobbe "knob," O.N. knyfill "short horn"). Meaning "knoll, isolated round hill" is first recorded 1650, especially in U.S.
knock (v.): O.E. cnocian (W.Saxon cnucian), likely of imitative origin. Meaning "deprecate, put down" is from 1892. Knockoff "cheap imitation" is from 1966. Knock out "to stun by a blow for a 10-count" in boxing is short for to knock out of time; slang knockout "attractive person" is from 1892. To knock oneself out "make a great effort" is from 1936. Knock-kneed first attested 1774. Command knock it off "stop it" is first recorded 1902. Knocker "door banger" is from 1598; knockers "a woman's breasts" is from 1941. Knock up is 1663 in sense of "arouse by knocking at the door;" however it is little used in this sense in Amer.Eng., where the phrase means "get a woman pregnant" (1813), possibly ult. from knock "to copulate with" (1598; cf. slang knocking-shop "brothel," 1860).
"Knocked up in the United States, amongst females, the phrase is equivalent to being enciente, so that Englishmen often unconsciously commit themselves when amongst our Yankee cousins." [John Camden Hotten, "The Slang Dictionary," London, 1860]
knoll: O.E. cnoll "hilltop, small hill," related to O.N. knollr "hilltop;" Ger. knolle "clod, lump;" Du. knol "turnip," nol "a hill."
knot: O.E. cnotta "intertwining of ropes, cords, etc.," from P.Gmc. *knuttan- (cf. Low Ger. knütte, Du. knot, O.H.G. knoto, Ger. Knoten, perhaps also O.N. knutr "knot, knob"). Fig. sense of "difficult problem" was in O.E. (cf. Gordian knot). Symbolic of the bond of wedlock, early 13c. As an ornament of dress, first attested c.1400. Meaning "thickened part or protuberance on tissue of a plant" is from late 14c. The nautical unit of measure (1630s) is from the practice of attaching knotted string to the log line. The ship's speed can be measured by the number of knots that play out while the sand glass is running.
"The distance between the knots on the log-line should contain 1/120 of a mile, supposing the glass to run exactly half a minute." [Jorge Juan and Antonio de Ulloa, "A Voyage to South America" 1760]
The verb meaning "to tie in a knot" is from 1547. Knot-hole is from 1726. Knothead "stupid person" is from 1940.
know: O.E. cnawan (class VII strong verb; past tense cneow, pp. cnawen), from P.Gmc. *knoeanan (cf. O.H.G. bi-chnaan, ir-chnaan "to know"), from PIE base *gno- "to know" (cf. O.Pers. xšnasatiy "he shall know;" O.C.S. znati, Rus. znat "to know;" L. gnoscere; Gk. *gno-, as in gignoskein; Skt. jna- "know"). Once widespread in Gmc., this form is now retained only in Eng., where however it has widespread application, covering meanings that require two or more verbs in other languages (e.g. Ger. wissen, kennen, erkennen and in part können; Fr. connaître, savoir; L. novisse, cognoscire, scire; O.C.S. znaja, vemi). The Anglo-Saxons used two distinct words for this, witan (see wit) and cnawan. Meaning "to have sexual intercourse with" is attested from c.1200, from the O.T. To not know one's ass from one's elbow is from 1930. To know better "to have learned from experience" is from 1704. You know as a parenthetical filler is from 1712, but it has roots in 14c. M.E. Know-how "technical expertise" first recorded 1838 in Amer.Eng. Know-nothing "ignoramus" is from 1827; as a U.S. nativist political party, active 1853-56, the name refers to the secret society at the core of the party, about which members were instructed to answer, if asked about it, that they "know nothing." The party merged into the Republican Party.
knowledge: M.E. cnawlece. For first element see know. Second element obscure, perhaps cognate with the -lock "action, process," found in wedlock.
knowledgeable: c.1600, "capable of being known;" from knowledge + -able. The modern sense of "having knowledge" is from 1829 and probably a new formation.
knuckle: late 14c., knokel "finger joint," common Gmc. (cf. M.L.G. knökel, M.Du. cnockel, Ger. knöchel), lit. "little bone," a dim. of P.Gmc. root *knuck- "bone" (cf. Ger. Knochen "bone). To knuckle down "apply oneself earnestly" is 1864 in Amer.Eng., extended from game of marbles; to knuckle under is first recorded 1740. Knuckle-duster is from 1858; knucklehead "stupid person" first recorded 1944. Knuckleball, type of baseball pitch, is from 1927.
knurl: 1608, probably a dim. of M.E. knor "knot" (c.1400), related to gnarl, from P.Gmc. *knur- (cf. Ger. knorren "a knotty excrescence").
koala: 1808, from the Aboriginal name of the animal, variously given as koola, kulla, kula.
koan: Zen paradox, 1946, from Jap. ko "public" + an "matter for thought."
Kodak: brand of camera, arbitrary coinage by U.S. inventor George Eastman (1854-1932), U.S. trademark reg. Sept. 4, 1888. In 1890s, practically synonymous with camera. Kodachrome, reg. trademark for a method of color photography, 1915.
koh-i-noor: famous diamond, one of the British crown jewels after the annexation of Punjab in 1849, from Pers. koh-i-nur, lit. "mountain of light," from Pers. koh "mountain" + Arabic nur "light."
kohl: "powder used to darken eyelids," 1799, from Arabic kuhl (see alcohol).
kohl rabi: kind of cabbage, 1807, from Ger. kohlrabi, from It. cavoli rape, pl. of cavolo rapa, lit. "cole rape" (see rape (n.)). Form influenced by Ger. kohl "cabbage."
koine: 1913, common literary dialect of Gk. in Roman and early medieval period, from Gk. fem. sing. of koinos "common, ordinary."
kola: "the cola nut," 1830, variant of cola (q.v.).
kolkhoz: U.S.S.R. collective farm, 1921, from Rus., contraction of kollektivnoe khozyaistvo "collective farm."
Komodo dragon: 1927, named for Indonesian island of Komodo, where it lives.
Komsomol: Rus. communist youth organization, 1934, from Rus., contraction of Kommunisticheskii Soyuz Molodezhi "Communist Union of Youth."
kooky: 1959, Amer.Eng., originally teenager or beatnik slang, possibly a shortening of cuckoo. Noun form kook is attested from 1960.
kopeck: 1/100 of a ruble, from Rus. kopeika, from kop'e "lance" (cognate with Gk. kopis "chopper, cleaver"); so called because the coin showed the czar with lance in hand.
Koran: 1615, from Arabic qur'an "a reading, recitation, book," from root of quara-a "he read, recited."
kos: measure of distance in India (about 2 miles), from Hindi kos, from Skt. krosah, lit. "a call, a shout;" thus, "distance within which a man's shout can be heard."
kosher: "ritually fit or pure" (especially of food), 1851, from Yiddish kosher, from Heb. kasher "fit, proper, lawful," from base of kasher "was suitable, proper." General sense of "correct, legitimate" is from 1896.
kowtow: 1804 (n.), from Chinese k'o-t'ou custom of touching the ground with the forehead to show respect or submission, lit. "knock the head," from k'o "knock, bump" + t'ou "head." The verb in the fig. sense of "act in an obsequious manner" is from 1826.
kraken: "monster of the North Sea," 1755, from Norw. dial. krake.
Kraut: "a German" (esp. a German soldier), 1841, but popularized during World War I, from Ger. kraut "cabbage," considered a characteristic national dish.
Kremlin: 1662, from Fr. kremlin, from Rus. krem'l "citadel, fortress," of Tartar origin. Originally the citadel of any Rus. city, now esp. the one in Moscow. Used metonymically for "government of the U.S.S.R." from 1933.
kriegspiel: war games played with pieces on maps, 1811, from Ger. Kriegsspiel, lit. "war game," from Krieg "war," from M.H.G. kriec, mostly "exertion, opposition, enmity," from O.H.G. krig "stubbornness, defiance," probably cognate with Gk. hybris "violence" (see hubris; cf. also war). For second element, see spiel (n.). Introduced 1870s as officer training in British army.
krill: 1907, from Norw. kril "small fry of fish."
kris: "short Malay dagger with a wavy blade," 1577, said to be a Javanese word.
Krishna: eighth avatar of Vishnu, 1875, from Skt. krshnah, lit. "the Black One," from PIE *kers-no-, suffixed form of base *kers- "dark, dirty" (cf. O.C.S. crunu, Rus. coron, Serbo-Cr. crn, Czech cerny, O.Prus. krisnas "black," Lith. kersas "black and white, variegated").
Kriss Kringle: 1830, Christ-kinkle (in a Pennsylvania German context), from Ger. Christkindlein, Christkind'l "Christ child." Properly Baby Jesus, not Santa Claus.