Online Etymology Dictionary

casino: 1744, "public room for music or dancing," from It. casino, dim. of casa "house," from L. casa "hut, shed," of uncertain origin. The card game is attested by that name from 1792.
cask: 1458, from M.Fr. casque "cask, helmet," from Sp. casco "skull, cask, helmet," orig. "potsherd," from cascar "to break up," from V.L. *quassicare, freq. of L. quassare "to shake, shatter" (see quash). The sense evolution is unclear.
casket: 1461, "small box for jewels, etc.," possibly formed as a dim. of Eng. cask, or from Norm.-Fr. cassette, from M.Fr. casset (see cassette). Meaning of "coffin" is Amer.Eng., probably euphemistic, first attested 1849.
"Caskets! a vile modern phrase, which compels a person ... to shrink ... from the idea of being buried at all." [Hawthorne, 1863]
casque: "armor for the head," 1580, from Fr., see cask.
Cassandra: Gk. kasandra, daughter of Priam of Troy, seduced by Apollo, who gave her the gift of prophecy, but when she betrayed him he amended it so that, though she spoke truth, none would believe her. Used figuratively since c.1668.
cassava: 1555, from Port. cassave, from Taino (Haiti) caçabi.
casserole: 1706, from Fr. casserole "sauce pan," dim. of M.Fr. casse "pan," from Prov. cassa "melting pan," from M.L. cattia, possibly from Gk. kyathion, dim. of kyathos "bowl, cup." Originally the pan, since 1958 also the dishes cooked in it.
cassette: 1793, "little box," from Fr. cassette, from M.Fr. casset, dim. of Norm.-Fr. casse "box" (see case (2)). Meaning "magnetic tape recorder cartridge" is from 1960.
cassia: cinnamon-like plant, late O.E., from L. cassia, from Gk. kasia, from Heb. q'tsi-ah, from qatsa "to cut off, strip off bark."
Cassiopeia: northern constellation, in Gk. mythology, queen of Ethiopia and mother of Andromeda, from Gk. Kassiepeia, of unknown origin.
cassis: black currant liquor, 1907, from Fr., apparently from L. cassia (see cassia).
Cassius: Roman gens, one of the oldest families of Rome. The conspirator against Caesar was C. Cassius Longinus.
cassock: c.1550, from M.Fr. casaque "long coat," probably ultimately from Turk. quzzak "nomad, adventurer," (the source of Cossack), an allusion to their typical riding coat. Or perhaps from Arabic kazagand, from Pers. kazhagand "padded coat," from kazh "raw silk" + agana "stuffed."
cassowary: 1611, from Fr. or Du., from Malay kasuari.
cast (v.): c.1230, from O.N. kasta "to throw." The noun sense of "a throw" (c.1300) carried an idea of the form the thing takes after it has been thrown, which led to varied meanings, such as "group of actors in a play" (1631). OED finds 42 distinct noun meaning and 83 verbal ones, with many sub-definitions. A cast in the eye preserves the older sense of "warp, turn," in which it replaced O.E. weorpan (see warp), and is itself largely superseded now by throw. Still used of fishing line and glances.
cast iron: 1660s, from cast (pp. adj.) "made by melting and being left to harden in a mold" (1530s), from cast (v.) in sense "to throw something in a particular way" (c.1300).
castanet: 1647, from Sp. castaneta dim. of castana "chestnut," from L. castanea.
castaway: 1526 (n.) "one who is rejected," from cast (v.) + away. Specific sense "one adrift at sea" is from 1799. The adj. is first recorded 1542.
caste: 1555, "a race of men," from L. casto "chaste," from castus "pure, cut off, separated," pp. of carere "to be cut off from" (and related to castrate), from PIE base *kes- "to cut."Application to Hindu social groups picked up in India 17c. from Port. casta "breed, race, caste," earlier casta raca "unmixed race," from the same L. word. Caste system is first recorded 1840.
castellated: "furnished with turrets and battlements," 1679, from M.L. castellatus, p.p. of castellare "to fortify as a castle," from L. castellum "fort" (see castle).
caster: "pepper shaker," 1676, on notion of "throwing;" meaning "wheel and swivel attached to furniture" is from 1748, from cast (q.v.) in the old sense of "turn."
castigate: 1607, from L. castigatus pp. of castigare "to purify, chastise," from castus "pure" (see caste) + agere "to do." Sense of "make someone pure by correcting or reproving him."
"If thou didst put this soure cold habit on To castigate thy pride, 'twere well." [Shakespeare, "Timon" IV.iii (1607)]
Castile: medieval Sp. kingdom, from V.L. castilla, from L. castella, pl. of castellum (see castle); so called in ref. to the many forts there during the Moorish wars.
castle: late O.E. castel, from O.N.Fr. castel, from L. castellum "fortified village," dim. of castrum "fort;" cognate with O.Ir. cather, Welsh caer "town" (and perhaps related to castrare "cut off"). This word had come to O.E. as ceaster and formed the -caster and -chester in place names. Sp. alcazar "castle" is from Arabic al-qasr, from L. castrum. The move in chess is recorded under this name from 1656. In early bibles, castle was used to translate Gk. kome "village," causing much confusion. Castles in Spain translated a 14c. Fr. term (the imaginary castles sometimes stood in Asia or Albania) and probably reflects the hopes of landless knights to establish themselves abroad.
castor: "beaver," late 14c., from O.Fr. castor, from L. castor "beaver," from Gk. Kastor "he who excels," one of the divine twins (with Pollux), worshipped by women in ancient Greece as a healer and preserver from disease. His name was given to secretions of the animal, used medicinally in ancient times. Through this association his name replaced the native L. word for "beaver," which was fiber. Modern castor oil is first recorded 1746; it is made from seeds of the plant Ricinus communis but supposedly possesses qualities (and taste) similar to those of beaver juice, and thus so named.
castrate (v.): 1613, from castration (q.v.). The fig. sense is attested earlier (1554). Castrated is recorded from 1613.
castration: c.1420, from L. castrationem, agent noun of castrare "to castrate, prune," related to *castrum "knife," from PIE base *kes- "to cut." Hence castrato (pl. castrati), borrowed 1763 from the It. form of the word. Freud's castration complex is 1914 in Eng.
casual: late 14c., "subject to or produced by chance," from O.Fr. casuel, from L.L. casualis "by chance," from L. casus "chance, event" (see case (1)). Of persons, in the sense of "not to be depended on, unmethodical," it is attested from 1883.
casualty: 1423, "chance, accident," from L. casualis (see casual) on model of royalty, penalty, etc. Casuality had some currency 16c.-17c. but is now obsolete. Meaning "losses in numbers from a military or other troop" is from 1494. Meaning an individual so lost is from 1844.
casuist: 1609, "one who studies and resolves cases of conscience," from Fr. casuiste, from L. casus (see case (1)). Often in a sinister or contemptuous sense. Casuistry is first attested 1725.
"Casuistry ... destroys, by distinctions and exceptions, all morality, and effaces the essential difference between right and wrong." [Bolingbroke, 1736]
casuistic: 1649, "pertaining to casuistry," from casuist (see casuist).
casuistry: 1725, from casuist (q.v.).
casus belli: 1849, from L. casus "case" + belli, gen. of bellum "war." An act justifying war.
cat: O.E. (c.700), from W.Gmc. (c.400-450), from P.Gmc. *kattuz, from L.L. cattus. The near-universal European word now, it appeared in Europe as L. catta (Martial, c.75 C.E.), Byzantine Gk. katta (c.350) and was in general use on the continent by c. 700, replacing L. feles. Probably ult. Afro-Asiatic (cf. Nubian kadis, Berber kadiska, both meaning "cat"). Arabic qitt "tomcat" may be from the same source. Cats were domestic in Egypt from c.2000 B.C.E., but not a familiar household animal to classical Greeks and Romans. The nine lives have been proverbial since at least 1560s. Extended to lions, tigers, etc. c.1600. As a term of contempt for a woman, from early 13c. Slang sense of "prostitute" is from at least c.1400. Slang sense of "fellow, guy," is from 1920, originally in U.S. Black Eng.; narrower sense of "jazz enthusiast" is recorded from 1931. Catnap is from 1823; catfish is from c.1620. Cat's-cradle is from 1768. Cat-o'-nine-tails (1690s), probably so called in reference to its "claws," was legal instrument of punishment in British Navy until 1881. Cat's paw (1769, but cat's foot in the same sense, 1597) refers to old folk tale in which the monkey tricks the cat into pawing chestnuts from a fire; the monkey gets the nuts, the cat gets a burnt paw. To rain cats and dogs (c.1652) is probably an extension of cats and dogs as proverbial for "strife, enmity" (1570s). Cat-witted "small-minded, obstinate, and spiteful" (1670s) deserved to survive. For Cat's meow, cat's pajamas, see bee's knees.
CAT: 1975, medical acronym for computerized axial tomography or something like it.
CAT scan: 1975; see CAT.
cata-: from Gk. kata-, before vowels kat-. Its principal sense is "down," but with occasional senses of "against" or "wrongly." Also sometimes used as an intensive. Most Eng. words with this prefix were borrowed through L. after 1500; e.g. catalectic (1589) "wanting a syllable in the last foot."
catabolic: 1876, from catabolism.
catabolism: 1876, "destructive metabolism," from Gk. katabole "a throwing down," from kataballein "to throw down," from kata- "down" + ballein "to throw" (see ballistics).
catachresis: 1589, from L. catachresis, from Gk. katakhresis "misuse" (of a word), from katakhresthai "to misuse," from kata- "down" (here with a sense of "perversion") + khresthai "to use" (see hortatory).
cataclysm: 1633, from Fr. cataclysme, from L. cataclysmos, from Gk. kataklysmos, from kata "down" + klyzein "to wash." Cataclysmic is attested from 1851.
catacomb: O.E. catacumbas, from L.L. (400 C.E.) catacumbae, originally the region of underground tombs between the 2nd and 3rd milestones of the Appian Way (where the bodies of apostles Paul and Peter were said to have been laid), origin obscure, perhaps once a proper name, or dissimilation from L. cata tumbas "at the graves," from cata- "among" + tumbas, acc. pl. of tumba "tomb." Extended 1836 to any subterranean receptacle of the dead (as in Paris).
catafalque: 1641, from Fr. catafalque, from It. catafalco "scaffold," from V.L. *catafalicum, from Gk. kata- "down," used in M.L. with a sense of "beside, alongside" + fala "scaffolding."
Catalan: 1480, from the indigenous name, which is of Celtic origin and probably means "chiefs of battle."
catalepsy: late 14c., cathalempsia, from M.L. catalepsia, from Gk. katalepsis "a seizing upon," from kataleptos "seized," from katalambanein "to seize upon," from kata- "down" + lambanein "to take" (see analemma).
cataleptic: 1684, from L.L. catalepticus, from Gk. kataleptikos, from kataleptos (see catalepsy). The noun meaning "one affected by catalepsy" is from 1851.
catalog: see catalogue.
catalogue: 1460, from L.L. catalogus, from Gk. katalogos "a list, register," from kata "down, completely" + legein "to say, count" (see lecture). The verb is first attested 1598.
catalpa: c.1740, from an American Indian language of the Carolinas, perhaps Creek (Muskogean) /katalpa/, lit. "head-wing."
catalyse: variant spelling of catalyze (q.v.); for suffix, see -ize.