Online Etymology Dictionary

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 cadge "to fasten, to tie" (late 14c.), which probably is from a Scandinavian source (compare Old Norse kögur-barn "swaddled child").
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.
Cadiz: from Latin Gades (Greek Gadeira), from Phoenician gadir "fort, enclosure." Related: Gaditan (from Latin adjective Gaditanus).
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. With metallic element ending -ium. 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" (source also of 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 Latin lactis, genitive of lac "milk" (see lacto-).
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).
Cajun: 1868, Cagian, dialectic pronunciation of Acadian, from Acadia, former French colony in what is now Canadian Maritimes. Its French setters were dispersed and exiled by the English and thousands made their way to New Orleans in the period 1764-1788.
cake (n.): early 13c., from Old Norse kaka "cake," from West Germanic *kokon- (source also of Middle Dutch koke, Dutch koek, Old High German huohho, German Kuchen). Not now believed to be related to Latin coquere "to cook," as formerly supposed. Replaced its Old English cognate, coecel.
What man, I trow ye raue, Wolde ye bothe eate your cake and haue your cake? ["The Proverbs & Epigrams of John Heywood," 1562]
Originally (until early 15c.) "a flat, round loaf of bread." Piece of cake "something easy" is from 1936. The let them eat cake story is found in Rousseau's "Confessions," in reference to an incident c. 1740, long before Marie Antoinette, though it has been associated with her since c. 1870; it apparently was a chestnut in the French royal family that had been told of other princesses and queens before her.
cake (v.): c. 1600, from cake (n.). Related: Caked; caking.
caked (adj.): "thickly encrusted," 1922, past participle adjective from cake (v.).
cakewalk (n.): 1863, American English, from cake (n.) + walk (n.), probably in reference to the cake given as a prize for the fanciest steps in a procession in a Southern black custom (explained by Thornton, 1912, as, "A walking competition among negroes," in which the prize cake goes to "the couple who put on most style"). Its figurative meaning of "something easy" (1863) is recorded before the literal one (1879). As a verb, from 1909. This may also be the source of the phrase to take the cake (1847).