cacophony (n.)
1650s, from Greek kakophonia, from kakophonos "harsh sounding," from kakos "bad, evil" (see caco-) + phone "voice" (see fame (n.)). Related: Cacophonous.
cactus (n.)
c.1600, from Latin cactus "cardoon," from Greek kaktos, name of a type of prickly plant of Sicily (the Spanish artichoke), perhaps of pre-Hellenic origin. Modern meaning is 18c., because Linnaeus gave the name to a group of plants he thought were related to this but are not.
cad (n.)
1730, shortening of cadet (q.v.); originally used of servants, then (1831) of town boys by students at British universities and public schools (though at Cambridge it meant "snob"). Meaning "person lacking in finer feelings" is from 1838.
A cad used to be a jumped-up member of the lower classes who was guilty of behaving as if he didn't know that his lowly origin made him unfit for having sexual relationships with well-bred women. [Anthony West, "H.G. Wells: Aspects of a Life," 1984]
cadastral (adj.)
1858, from French cadastral, from cadastre "register of the survey of lands" (16c.), from Old Italian catastico, from Late Greek katastikhos "register," literally "by the line" (see cata-, stair). Gamillscheg dismisses derivation from Late Latin capitastrum "register of the poll tax."
cadaver (n.)
c.1500, from Latin cadaver "dead body (of men or animals)," probably from a perfective participle of cadere "to fall, sink, settle down, decline, perish" (see case (n.1)). Compare Greek ptoma "dead body," literally "a fall" (see ptomaine); poetic English the fallen "those who died in battle."
cadaverous (adj.)
"looking like a corpse," early 15c., from Latin cadaverosus "corpse-like," from cadaver (see cadaver). Related: Cadaverously; cadaverousness.
caddie (n.)
1630s, Scottish form of French cadet (see cadet). Originally "person who runs errands;" meaning of "golfer's assistant" is 1851. A letter from Edinburgh c.1730 describes the city's extensive and semi-organized "Cawdys, a very useful Black-Guard, who attend ... publick Places to go at Errands; and though they are Wretches, that in Rags lye upon the Stairs and in the Streets at Night, yet are they often considerably trusted .... This Corps has a kind of Captain ... presiding over them, whom they call the Constable of the Cawdys."
caddis (n.)
"larva of the May-fly," 1650s, of unknown origin, perhaps a diminutive of some sense of cad.
caddy (n.)
"small box for tea," 1792, from Malay kati a weight equivalent to about a pound and a third (in English from 1590s as catty), adopted as a standard mid-18c. by British companies in the East Indies. Apparently the word for a measure of tea was transferred to the chest it was carried in.
cade (adj.)
"pet, tame," mid-15c., used in reference to young animals abandoned by their mothers and brought up by hand; of unknown origin.
cadence (n.)
late 14c., "flow of rhythm in verse or music," from Middle French cadence, from Old Italian cadenza "conclusion of a movement in music," literally "a falling," from Vulgar Latin *cadentia, from neuter plural of Latin cadens, present participle of cadere "to fall" (see case (n.1)). In 16c., sometimes used literally for "an act of falling." A doublet of chance (n.).
cadenza (n.)
"ornamental passage near the close of a song or solo," 1836, from Italian cadenza (see cadence).
cadet (n.)
c.1610, "younger son or brother," from French cadet "military student officer," noun use of adjective, "younger" (15c.), from Gascon capdet "captain, chief, youth of a noble family," from Late Latin capitellum, literally "little chief," hence, "inferior head of a family," diminutive of Latin caput "head" (see capitulum). "The eldest son being regarded as the first head of the family, the second son the cadet, or little head" [Kitchin].

Apparently younger sons from Gascon noble families were sent to French court to serve as officers, which gave the word its military meaning. In English, the meaning "gentleman entering the military as a profession" is from 1650s, and that of "student at a military college" is from 1775.
cadge (v.)
"to beg" (1812), "to get by begging" (1848), of uncertain origin, perhaps a back-formation from cadger "itinerant dealer with a pack-horse," mid-15c., which is perhaps from early 14c. cadge "to fasten, to tie," of unknown origin.
Cadillac (n.)
Cadillac Automobile Company, established in 1902 by Detroit engine-maker Henry Martyn Leland and named for Antoine de la Mothe Cadillac (1658-1730), French minor aristocrat and colonial governor who founded Detroit in 1701.
Cadmean victory (n.)
c.1600, "victory involving one's own ruin," translating Greek Kadmeia nike, from Cadmus (Greek Kadmos), legendary founder of Thebes in Boeotia and bringer of the alphabet to Greece. Probably a reference to the story of Cadmus and the "Sown-Men," who fought each other till only a handful were left alive. Compare Pyrrhic (adj.1).
cadmium (n.)
bluish-white metal, 1822, discovered 1817 by German scientist Friedrich Strohmeyer, coined in Modern Latin from cadmia, a word used by ancient naturalists for various earths and oxides (especially zinc carbonate), from Greek kadmeia (ge) "Cadmean (earth)," from Kadmos "Cadmus," legendary founder of Boeotian Thebes. So called because the earth was first found in the vicinity of Thebes (Kadmeioi was an alternative name for "Thebans" since the time of Homer).
cadre (n.)
1830, from French cadre, literally "a frame of a picture" (16c.), so, "a detachment forming the skeleton of a regiment" (1851), from Italian quadro, from Latin quadrum "a square" (see quadrille). The communist sense is from 1930.
caduceus (n.)
1590s, from Latin caduceus, alteration of Doric Greek karykeion "herald's staff," from karyx (genitive karykos) "a herald," from PIE *karu-, from root *kar- "to praise loudly, extol" (cognates: Sanskrit carkarti "mentions with praise," Old English hreð "fame, glory"). Token of a peaceful embassy; originally an olive branch. Especially the wand carried by Mercury, messenger of the gods, usually represented with two serpents twined round it.
cady (n.)
"hat, cap," 1846, of unknown origin.
caecum (n.)
1721, from Latin intestinum caecum "blind gut," from neuter of caecus "blind, hidden," from Proto-Italic *kaiko-, from PIE *kehi-ko- "one-eyed," cognate with Old Irish ca'ech "one-eyed," coeg "empty," Welsh coeg-dall, Old Cornish cuic "one-eyed;" Gothic haihs "one-eyed, blind." So called for being prolonged into a cul-de-sac.
Caesar
c.1200, see caesarian; Old English had casere, which would have yielded modern *coser, but it was replaced in Middle English by keiser, from Norse or Low German, and later in Middle English by the French or Latin form of the name. Cæsar was used as a title of emperors down to Hadrian (138 C.E.), and also is the root of German Kaiser and Russian tsar (see czar). He competes as progenitor of words for "king" with Charlemagne (Latin Carolus), as in Lithuanian karalius, Polish krol. In U.S. slang c.1900, a sheriff was Great Seizer.
Caesar salad
1952, said to be named not for the emperor, but for Cesar Cardini, restaurant owner in Tijuana, Mexico, who is said to have served the first one c.1924.
Caesarea
Latin city name derived from Caesar, applied in honor of the emperors to some new and existing cities in the Roman Empire, including modern Kayseri, Turkey; Shaizar, Syria, and Cherchell, Algeria (representing a French spelling of an Arabic name based on a Berber garbling of the Latin word).
caesarean
see caesarian.
caesarian (n.)
1923, shortening of Caesarian section (1610s); supposedly from Caius Julius Caesar, who was said to have been delivered surgically, thus legend traces his cognomen to Latin caesus past participle of caedere "to cut" (see -cide).

But if this is the etymology of the name, it was likely an ancestor who was so born (Caesar's mother lived to see his triumphs and such operations would have been fatal to the woman in ancient times). And Pliny derives his cognomen from caesaries "head of hair," because the future dictator was born with a full one. Caesarian section may come directly from caesus.
caesium (n.)
see cesium.
caesura (n.)
1550s, from Latin caesura, "metrical pause," literally "a cutting," from past participle stem of caedere "to cut down" (see -cide).
cafe (n.)
1802, from French café "coffee, coffeehouse," from Italian caffe "coffee" (see coffee). The beverage was introduced in Venice by 1615 and in France from 1650s by merchants and travelers who had been to Turkey and Egypt. The first public café might have been the one opened in Marseilles in 1660.
cafe au lait (n.)
1763, French café au lait, literally "coffee with milk," from lait "milk" (12c.), from Vulgar Latin lactis, from Latin lactis (see lactation).
cafeteria (n.)
1839, American English, from Mexican Spanish cafeteria "coffee store," from café "coffee" (see coffee) + Spanish -tería "place where something is done" (usually business). The ending came to be understood popularly as meaning "help-yourself" (as though café + -teria) and was extended to new formation with that sense from c.1923.
caffeine (n.)
trimethyl-derivative of xanthine, 1830, from German Kaffein, coined by chemist F.F. Runge (1795-1867), apparently from German Kaffee "coffee" (see coffee) + chemical suffix -ine (2) (German -in). The form of the English word may be via French caféine.
caftan (n.)
1590s, "long tunic worn in Turkey, etc.," from Turkish qaftan (also in Arabic), from Persian khaftan. As a similar shirt or dress style in the West, it is attested from c.1955.
cage (n.)
early 13c., from Old French cage "cage, prison; retreat, hideout" (12c.), from Latin cavea "hollow place, enclosure for animals, coop, hive, stall, dungeon, spectators' seats in the theater" (source also of Italian gabbia "basket for fowls, coop;" see cave (n.)).
cage (v.)
1570s, from cage (n.). Related: Caged; caging.
cagey (adj.)
"evasive, reticent," 1896, U.S. colloquial, of unknown origin. Earlier in English dialect it meant "sportive."
cahier (n.)
"exercise book," c.1845, from French cahier "writing book, copy-book," from Old French cayer, originally quaier "sheet of paper folded in four" (see quire).
cahoot
see cahoots.
cahoots (n.)
1829, American English, of unknown origin; said to be perhaps from French cahute "cabin, hut" (12c.), but U.S. sources credit it to French cohorte (see cohort), a word said to have been in use in the U.S. South and West with a sense of "companions, confederates."
caiman (n.)
also cayman, 1570s, from Portuguese or Spanish caiman, from Carib acayouman "crocodile," or perhaps from a Congo African word applied to the reptiles in the new world by African slaves. "The name appears to be one of those like anaconda and bom, boma, which the Portuguese or Spaniards very early caught up in one part of the world, and naturalized in another." [OED]
Cain
elder son of Adam and Eve, from Hebrew Qayin, literally "created one," also "smith," from Semitic stem q-y-n "to form, to fashion." To raise Cain is first recorded 1840. Surnames McCain, McCann, etc., are a contraction of Irish Mac Cathan "son of Cathan," from Celtic cathan, literally "warrior," from cath "battle."
cairn (n.)
1530s, from Scottish carne, from Gaelic carn "heap of stones, rocky hill," akin to Gaulish karnon "horn," perhaps from PIE *ker-n- "highest part of the body, horn," thus "tip, peak" (see horn (n.)).
Cairo
city in Egypt, from Arabic al-Kahira "the strong," the name given 973 C.E. to the new city built north of the old one, Egyptian khere-ohe, said to mean "place of combat" and to be in reference to a battle between the gods Seth and Horus that took place here.
caisson (n.)
1704, from French caisson "ammunition wagon, box, crate," from Middle French caisson "large box" (16c.), from Italian cassone, augmentative form of cassa "a chest," from Latin capsa "a box" (see case (n.2)).
caitiff (adj.)
c.1300, "wicked, base, cowardly," from Old North French caitive "captive, miserable" (Old French chaitif, 12c., Modern French chétif "puny, sickly, poor, weak"), from Latin captivum (see captive, which was a later, scholarly borrowing of the same word). In most Romance languages, it has acquired a pejorative sense.
caitiff (n.)
c.1300, "wicked man, scoundrel," from Anglo-French caitif, noun use from Old North French caitive "captive, miserable" (see caitiff (adj.)). From mid-14c as "prisoner."
Caitlin
fem. proper name, alternative spelling of Kathleen, not much used in U.S. then suddenly popular from c.1985.
Caius
variant of Gaius, common Roman praenomen. Both forms have the abbreviation C., and the confusion reflects the early Roman uncertainty about the use of gamma (see C).
cajole (v.)
1640s, from French cajoler "to cajole, wheedle, coax," perhaps a blend of Middle French cageoler "to chatter like a jay" (16c., from gajole, southern diminutive of geai "jay;" see jay (n.)), and Old French gaioler "to cage, entice into a cage" (see jail (n.)). Related: Cajoled; cajoling.
cajolery (n.)
1640s, from French cajolerie "persuasion by flattery" (16c.), from cajoler (see cajole).